2015- ...: Associate professor 2009-2014: Ramón y Cajal Fellowship 2008-2009: Juan de la Cierva Fellowship 2006-2007: MEC Fellowship “Programa de estancias de jóvenes doctores extranjeros en España” 2004-2006: postdoc in BEC Center, Trento, Italy 2002-2005: PhD at Institute of Spectroscopy (Russian Academy of Sciences), supervisor (Yu. E. Lozovik) 2001-2004: PhD at Università degli studi di Trento, Italia (supervisors: Stefano Giorgini and Lev Pitaevskii) 2000-2001: Student at Università degli studi di Trento, Italy 1996-2002: Student at Moscow Institute of Physics and Technology, Russia

2011 – : Lecturer – General Physics 2011 – : Seminars teacher – General Physics 2008 – : Laboratory teacher – General Physics, Universitat Politècnica de Catalunya / Spain

Publications

[1] L. Parisi, G. E. Astrakharchik, S. Giorgini, The liquid state of one-dimensional Bose mixtures: a quantum Monte-Carlo study, (2019) [arXiv][abstract]

@ARTICLE{LParisi,-Thel-2019, author = {L. Parisi and G. E. Astrakharchik and S. Giorgini}, title = {The liquid state of one-dimensional Bose mixtures: a quantum Monte-Carlo study}, year = {2019} }

AUTORES/AS (p.o. de firma): L. Parisi, G. E. Astrakharchik, S. Giorgini TITULO: The liquid state of one-dimensional Bose mixtures: a quantum Monte-Carlo study REF REVISTA/LIBRO: , CLAVE: A FECHA PUBLICACION (*): 2019

[2] V. Cikojevic, L. Vranjes-Markic, G. E. Astrakharchik,
J. Boronat, Universality in ultradilute liquid Bose-Bose mixtures, Phys. Rev. A99, 023618 (2018) [journal] [arXiv][abstract]

We have studied dilute Bose-Bose mixtures of atoms with attractive interspecies and repulsive intraspecies interactions using quantum Monte Carlo methods at T=0. Using a number of models for interactions, we determine the range of validity of the universal equation of state of the symmetric liquid mixture as a function of two parameters: the
s-wave scattering length and the effective range of the interaction potential. It is shown that the Lee-Huang-Yang correction is sufficient only for extremely dilute liquids with the additional restriction that the range of the potential is small enough. Based on the quantum Monte Carlo equation of state we develop a density functional which goes beyond the Lee-Huang-Yang term and use it together with the local density approximation to determine density profiles of realistic self-bound drops.

@ARTICLE{VCikoje-Unive-2018, author = { V. Cikojevic and L. Vranjes-Markic and G. E. Astrakharchik and
J. Boronat}, title = {Universality in ultradilute liquid Bose-Bose mixtures}, journal = {Phys. Rev. A}, volume = {99}, pages = {023618}, year = {2018} }

AUTORES/AS (p.o. de firma): V. Cikojevic, L. Vranjes-Markic, G. E. Astrakharchik,
J. Boronat TITULO: Universality in ultradilute liquid Bose-Bose mixtures REF REVISTA/LIBRO: Phys. Rev. A 99, 023618 CLAVE: A FECHA PUBLICACION (*): 2018

[3] G. E. Astrakharchik and B. A. Malomed, Dynamics of one-dimensional quantum droplets, Phys. Rev. A98, 013631 (2018) [journal][abstract]

The structure and dynamics of one-dimensional binary Bose gases forming quantum droplets is studied by solving the corresponding amended Gross-Pitaevskii equation. Two physically different regimes are identified, corresponding to small droplets of an approximately Gaussian shape and large `puddles' with a broad flat-top plateau. Small droplets collide quasi-elastically, featuring the soliton-like behavior. On the other hand, large colliding droplets may merge or suffer fragmentation, depending on their relative velocity. The frequency of a breathing excited state of droplets, as predicted by the dynamical variational approximation based on the Gaussian ansatz, is found to be in good agreement with numerical results. Finally, the stability diagram for a single droplet with respect to shape excitations with a given wave number is drawn, being consistent with preservation of the Weber number for large droplets.

@ARTICLE{GEAstr-Dynam-2018, author = {G. E. Astrakharchik and B. A. Malomed}, title = {Dynamics of one-dimensional quantum droplets}, journal = {Phys. Rev. A}, volume = {98}, pages = {013631}, year = {2018} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik and B. A. Malomed TITULO: Dynamics of one-dimensional quantum droplets REF REVISTA/LIBRO: Phys. Rev. A 98, 013631 CLAVE: A FECHA PUBLICACION (*): 2018

[4] G. E. Astrakharchik, P. S. Kryuchkov, I. L. Kurbakov, Yu. E. Lozovik, The Inverse-Square Interaction Phase Diagram: Unitarity in the Bosonic Ground State, Crystals8, 246 (2018) [journal][abstract]

Ground-state properties of bosons interacting via inverse square potential (three dimensional Calogero-Sutherland model) are analyzed. A number of quantities scale with the density and can be naturally expressed in units of the Fermi energy and Fermi momentum multiplied by a dimensionless constant (Bertsch parameter). Two analytical approaches are developed: the Bogoliubov theory for weak and the harmonic approximation (HA) for strong interactions. Diffusion Monte Carlo method is used to obtain the ground-state properties in a non-perturbative manner. We report the dependence of the Bertsch parameter on the interaction strength and construct a Pad\'e approximant which fits the numerical data and reproduces correctly the asymptotic limits of weak and strong interactions. We find good agreement with beyond-mean field theory for the energy and the condensate fraction. The pair distribution function and the static structure factor are reported for a number of characteristic interactions. We demonstrate that the system experiences a gas-solid phase transition as a function of the dimensionless interaction strength. A peculiarity of the system is that by changing the density it is not possible to induce the phase transition. We show that the low-lying excitation spectrum contains plasmons in both phases, in agreement with the Bogoliubov and HA theories. Finally, we argue that this model can be interpreted as a realization of the unitary limit of a Bose system with the advantage that the system stays in the genuine ground state contrarily to the metastable state realized in experiments with short-range Bose gases.

@ARTICLE{GEAstr-TheI-2018, author = {G. E. Astrakharchik and P. S. Kryuchkov and I. L. Kurbakov and Yu. E. Lozovik}, title = {The Inverse-Square Interaction Phase Diagram: Unitarity in the Bosonic Ground State}, journal = {Crystals}, volume = {8}, pages = {246}, year = {2018} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, P. S. Kryuchkov, I. L. Kurbakov, Yu. E. Lozovik TITULO: The Inverse-Square Interaction Phase Diagram: Unitarity in the Bosonic Ground State REF REVISTA/LIBRO: Crystals 8, 246 CLAVE: A FECHA PUBLICACION (*): 2018

[5] G. Guijarro, A. Pricoupenko, G. E. Astrakharchik, J. Boronat, D. S. Petrov, One-dimensional three-boson problem with two- and three-body interactions, Phys. Rev. A97, 061605(R) (2018)[abstract]

@ARTICLE{GGuijarr-One-d-2018, author = {G. Guijarro and A. Pricoupenko and G. E. Astrakharchik and J. Boronat and D. S. Petrov}, title = {One-dimensional three-boson problem with two- and three-body interactions}, journal = {Phys. Rev. A}, volume = {97}, pages = {061605(R)}, year = {2018} }

AUTORES/AS (p.o. de firma): G. Guijarro, A. Pricoupenko, G. E. Astrakharchik, J. Boronat, D. S. Petrov TITULO: One-dimensional three-boson problem with two- and three-body interactions REF REVISTA/LIBRO: Phys. Rev. A 97, 061605(R) CLAVE: A FECHA PUBLICACION (*): 2018

[6] L. Parisi, G. E. Astrakharchik, and S. Giorgini, Spin Dynamics and Andreev-Bashkin Effect in Mixtures of One-Dimensional Bose Gases, Phys. Rev. Lett.121, 025302 (2018) [journal][abstract]

We investigate the propagation of spin waves in two-component mixtures of one-dimensional Bose gases interacting through repulsive contact potentials. By using quantum Monte Carlo methods we calculate static ground-state properties, such as the spin susceptibility and the spin structure factor, as a function of both the intra-species and inter-species coupling strength and we determine the critical parameters for phase separation. In homogeneous mixtures, results of the velocity of spin waves and of its softening close to the critical point of phase separation are obtained by means of a sum-rule approach. We quantify the non-dissipative drag effect, resulting from the Andreev-Bashkin current-current interaction between the two components of the gas, and we show that in the regime of strong coupling it causes a significant suppression of the spin-wave velocity.

@ARTICLE{LParisi,-Spin-2018, author = {L. Parisi and G. E. Astrakharchik and S. Giorgini}, title = {Spin Dynamics and Andreev-Bashkin Effect in Mixtures of One-Dimensional Bose Gases}, journal = {Phys. Rev. Lett.}, volume = {121}, pages = {025302}, year = {2018} }

AUTORES/AS (p.o. de firma): L. Parisi, G. E. Astrakharchik, and S. Giorgini TITULO: Spin Dynamics and Andreev-Bashkin Effect in Mixtures of One-Dimensional Bose Gases REF REVISTA/LIBRO: Phys. Rev. Lett. 121, 025302 CLAVE: A FECHA PUBLICACION (*): 2018

[7] A.E. Golomedov, Yu. E. Lozovik, G.E. Astrakharchik and J. Boronat, Composite Boson Description of a Low-Density Gas of Excitons, J. Low. Temp. Phys.189, 300 (2017)[abstract]

@ARTICLE{AEGolom-Compo-2017, author = {A.E. Golomedov and Yu. E. Lozovik and G.E. Astrakharchik and J. Boronat}, title = {Composite Boson Description of a Low-Density Gas of Excitons}, journal = {J. Low. Temp. Phys.}, volume = {189}, pages = {300}, year = {2017} }

AUTORES/AS (p.o. de firma): A.E. Golomedov, Yu. E. Lozovik, G.E. Astrakharchik and J. Boronat TITULO: Composite Boson Description of a Low-Density Gas of Excitons REF REVISTA/LIBRO: J. Low. Temp. Phys. 189, 300 CLAVE: A FECHA PUBLICACION (*): 2017

[8] Fabian Grusdt, Gregory E Astrakharchik and Eugene Demler, Bose polarons in ultracold atoms in one dimension: beyond the Fröhlich paradigm, New Journal of Physics19, 103035 (2017) [journal][abstract]

@ARTICLE{FabianGru-Bose-2017, author = {Fabian Grusdt and Gregory E Astrakharchik and Eugene Demler}, title = {Bose polarons in ultracold atoms in one dimension: beyond the Fröhlich paradigm}, journal = {New Journal of Physics}, volume = {19}, pages = {103035}, year = {2017} }

AUTORES/AS (p.o. de firma): Fabian Grusdt, Gregory E Astrakharchik and Eugene Demler TITULO: Bose polarons in ultracold atoms in one dimension: beyond the Fröhlich paradigm REF REVISTA/LIBRO: New Journal of Physics 19, 103035 CLAVE: A FECHA PUBLICACION (*): 2017

[9] Giulia De Rosi, Grigori E. Astrakharchik, and Sandro Stringari, Thermodynamic behavior of a one-dimensional Bose gas at low temperature, Phys. Rev. A96, 013613 (2017) [journal][abstract]

@ARTICLE{GiuliaDe-Therm-2017, author = {Giulia De Rosi and Grigori E. Astrakharchik and Sandro Stringari}, title = {Thermodynamic behavior of a one-dimensional Bose gas at low temperature}, journal = {Phys. Rev. A}, volume = {96}, pages = {013613}, year = {2017} }

AUTORES/AS (p.o. de firma): Giulia De Rosi, Grigori E. Astrakharchik, and Sandro Stringari TITULO: Thermodynamic behavior of a one-dimensional Bose gas at low temperature REF REVISTA/LIBRO: Phys. Rev. A 96, 013613 CLAVE: A FECHA PUBLICACION (*): 2017

[10] Grigory E. Astrakharchik, Konstantin V. Krutitsky, Maciej Lewenstein, Ferran Mazzanti, Jordi Boronat, Optical lattices as a tool to study defect-induced superfluidity, Phys. Rev. A96, 033606 (2017) [journal][abstract]

@ARTICLE{GrigoryE-Optic-2017, author = {Grigory E. Astrakharchik and Konstantin V. Krutitsky and Maciej Lewenstein and Ferran Mazzanti and Jordi Boronat}, title = {Optical lattices as a tool to study defect-induced superfluidity}, journal = {Phys. Rev. A}, volume = {96}, pages = {033606}, year = {2017} }

AUTORES/AS (p.o. de firma): Grigory E. Astrakharchik, Konstantin V. Krutitsky, Maciej Lewenstein, Ferran Mazzanti, Jordi Boronat TITULO: Optical lattices as a tool to study defect-induced superfluidity REF REVISTA/LIBRO: Phys. Rev. A 96, 033606 CLAVE: A FECHA PUBLICACION (*): 2017

[11] Jacopo Nespolo, Grigori E. Astrakharchik, Alessio Recati, Andreev-Bashkin effect in superfluid cold gases mixture, New J. Phys.19, 125005 (2017) [journal][abstract]

@ARTICLE{JacopoNes-Andre-2017, author = {Jacopo Nespolo and Grigori E. Astrakharchik and Alessio Recati}, title = {Andreev-Bashkin effect in superfluid cold gases mixture}, journal = {New J. Phys.}, volume = {19}, pages = {125005}, year = {2017} }

AUTORES/AS (p.o. de firma): Jacopo Nespolo, Grigori E. Astrakharchik, Alessio Recati TITULO: Andreev-Bashkin effect in superfluid cold gases mixture REF REVISTA/LIBRO: New J. Phys. 19, 125005 CLAVE: A FECHA PUBLICACION (*): 2017

[12] Marek Tylutki, G. E. Astrakharchik, Alessio Recati, Coherent Oscillations in Small Fermi Polaron Systems, Phys. Rev. A96, 063603 (2017) [journal][abstract]

@ARTICLE{MarekTylu-Coher-2017, author = {Marek Tylutki and G. E. Astrakharchik and Alessio Recati}, title = {Coherent Oscillations in Small Fermi Polaron Systems}, journal = {Phys. Rev. A}, volume = {96}, pages = {063603}, year = {2017} }

AUTORES/AS (p.o. de firma): Marek Tylutki, G. E. Astrakharchik, Alessio Recati TITULO: Coherent Oscillations in Small Fermi Polaron Systems REF REVISTA/LIBRO: Phys. Rev. A 96, 063603 CLAVE: A FECHA PUBLICACION (*): 2017

[13] A. J. Vidal, G. E. Astrakharchik, L. Vranješ Markić, and J. Boronat, One Dimensional 1H, 2H and 3H, New J. Phys.18, 055013 (2016) [journal][abstract]

The ground-state properties of one-dimensional electron-spin-polarized hydrogen 1H, deuterium 2H, and tritium 3H are obtained by means of quantum Monte Carlo methods. The equations of state of the three isotopes are calculated for a wide range of linear densities. The pair correlation function and the static structure factor are obtained and interpreted within the framework of the Luttinger liquid theory. We report the density dependence of the Luttinger parameter and use it to identify different physical regimes: Bogoliubov Bose gas, super-Tonks–Girardeau gas, and quasi-crystal regimes for bosons; repulsive, attractive Fermi gas, and quasi-crystal regimes for fermions. We find that the tritium isotope is the one with the richest behavior. Our results show unambiguously the relevant role of the isotope mass in the properties of this quantum system.

@ARTICLE{AJVida-OneD-2016, author = {A. J. Vidal and G. E. Astrakharchik and L. Vranješ Markić and J. Boronat}, title = {One Dimensional 1H, 2H and 3H}, journal = {New J. Phys.}, volume = {18}, pages = {055013 }, year = {2016} }

AUTORES/AS (p.o. de firma): A. J. Vidal, G. E. Astrakharchik, L. Vranješ Markić, and J. Boronat TITULO: One Dimensional 1H, 2H and 3H REF REVISTA/LIBRO: New J. Phys. 18, 055013 CLAVE: A FECHA PUBLICACION (*): 2016

[14] D. S. Petrov, G. E. Astrakharchik, Ultradilute low-dimensional liquids, Phys. Rev. Lett.117, 100401 (2016) [journal][abstract]

@ARTICLE{DSPetr-Ultra-2016, author = {D. S. Petrov and G. E. Astrakharchik}, title = {Ultradilute low-dimensional liquids}, journal = {Phys. Rev. Lett.}, volume = {117}, pages = {100401}, year = {2016} }

AUTORES/AS (p.o. de firma): D. S. Petrov, G. E. Astrakharchik TITULO: Ultradilute low-dimensional liquids REF REVISTA/LIBRO: Phys. Rev. Lett. 117, 100401 CLAVE: A FECHA PUBLICACION (*): 2016

[15] G. E. Astrakharchik, R. E. Zillich, F. Mazzanti, J. Boronat, Gapped spectrum in pair-superfluid bosons, Phys. Rev. A94, 063630 (2016)[abstract]

@ARTICLE{GEAstr-Gappe-2016, author = {G. E. Astrakharchik and R. E. Zillich and F. Mazzanti and J. Boronat}, title = {Gapped spectrum in pair-superfluid bosons}, journal = {Phys. Rev. A}, volume = {94}, pages = {063630}, year = {2016} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, R. E. Zillich, F. Mazzanti, J. Boronat TITULO: Gapped spectrum in pair-superfluid bosons REF REVISTA/LIBRO: Phys. Rev. A 94, 063630 CLAVE: A FECHA PUBLICACION (*): 2016

[16] Grigory E. Astrakharchik, Konstantin V. Krutitsky, Maciej Lewenstein, Ferran Mazzanti, One-dimensional Bose gas in optical lattices of arbitrary strength, Phys. Rev. A93, 021605(R) (2016) [journal][abstract]

@ARTICLE{GrigoryE-One-d-2016, author = {Grigory E. Astrakharchik and Konstantin V. Krutitsky and Maciej Lewenstein and Ferran Mazzanti}, title = {One-dimensional Bose gas in optical lattices of arbitrary strength}, journal = {Phys. Rev. A}, volume = {93}, pages = {021605(R)}, year = {2016} }

AUTORES/AS (p.o. de firma): Grigory E. Astrakharchik, Konstantin V. Krutitsky, Maciej Lewenstein, Ferran Mazzanti TITULO: One-dimensional Bose gas in optical lattices of arbitrary strength REF REVISTA/LIBRO: Phys. Rev. A 93, 021605(R) CLAVE: A FECHA PUBLICACION (*): 2016

[17] N. Matveeva, G. E. Astrakharchik, One-dimensional multicomponent Fermi gas in a trap: quantum Monte Carlo study, New J. Phys.18, 065009 (2016) [journal][abstract]

One-dimensional world is very unusual as there is an interplay between quantum statistics and geometry, and a strong short-range repulsion between atoms mimics Fermi exclusion principle, fermionizing the system. Instead, a system with a large number of components with a single atom in each, on the opposite acquires many bosonic properties. We study the ground-state properties a multi-component Fermi gas trapped in a harmonic trap by fixed-node diffusion Monte Carlo method. We investigate how the energetic properties (energy, contact) and correlation functions (density profile and momentum distribution) evolve as the number of components is changed. It is shown that the system fermionizes in the limit of strong interactions. Analytical expression are derived in the limit of weak interactions within the local density approximation for arbitrary number of components and for one plus one particle using an exact solution.

@ARTICLE{NMatveev-One-d-2016, author = {N. Matveeva and G. E. Astrakharchik}, title = {One-dimensional multicomponent Fermi gas in a trap: quantum Monte Carlo study}, journal = {New J. Phys.}, volume = {18}, pages = {065009}, year = {2016} }

AUTORES/AS (p.o. de firma): N. Matveeva, G. E. Astrakharchik TITULO: One-dimensional multicomponent Fermi gas in a trap: quantum Monte Carlo study REF REVISTA/LIBRO: New J. Phys. 18, 065009 CLAVE: A FECHA PUBLICACION (*): 2016

[18] Yaroslav Lutsyshyn, Grigori E. Astrakharchik, SAIL: A CUDA-based implementation of the simulated annealing for the inverse Laplace transform problem, arXiv:1609.07936 (2016)[abstract]

@ARTICLE{YaroslavL-SAIL:-2016, author = {Yaroslav Lutsyshyn and Grigori E. Astrakharchik}, title = {SAIL: A CUDA-based implementation of the simulated annealing for the inverse Laplace transform problem}, journal = {arXiv:1609.07936}, year = {2016} }

AUTORES/AS (p.o. de firma): Yaroslav Lutsyshyn, Grigori E. Astrakharchik TITULO: SAIL: A CUDA-based implementation of the simulated annealing for the inverse Laplace transform problem REF REVISTA/LIBRO: arXiv:1609.07936 , CLAVE: A FECHA PUBLICACION (*): 2016

[19] A. del Campo, M. Olshanii, G. Astrakharchik , Marvin Denham Girardeau, Physics Today68, 64 (2015) [journal][abstract]

@ARTICLE{AdelCam-Marvi-2015, author = {A. del Campo and M. Olshanii and G. Astrakharchik }, title = {Marvin Denham Girardeau}, journal = {Physics Today}, volume = {68}, pages = {64}, year = {2015} }

AUTORES/AS (p.o. de firma): A. del Campo, M. Olshanii, G. Astrakharchik TITULO: Marvin Denham Girardeau REF REVISTA/LIBRO: Physics Today 68, 64 CLAVE: A FECHA PUBLICACION (*): 2015

[20] A. Iu. Gudyma, G. E. Astrakharchik, Mikhail B. Zvonarev, Reentrant behavior of the breathing-mode-oscillation frequency in a one-dimensional Bose gas, Phys. Rev. A92, 021601(R) (2015) [journal][abstract]

@ARTICLE{AIuGud-Reent-2015, author = {A. Iu. Gudyma and G. E. Astrakharchik and Mikhail B. Zvonarev}, title = {Reentrant behavior of the breathing-mode-oscillation frequency in a one-dimensional Bose gas}, journal = {Phys. Rev. A}, volume = {92}, pages = {021601(R)}, year = {2015} }

AUTORES/AS (p.o. de firma): A. Iu. Gudyma, G. E. Astrakharchik, Mikhail B. Zvonarev TITULO: Reentrant behavior of the breathing-mode-oscillation frequency in a one-dimensional Bose gas REF REVISTA/LIBRO: Phys. Rev. A 92, 021601(R) CLAVE: A FECHA PUBLICACION (*): 2015

[21] G. E. Astrakharchik and B. A. Malomed, Quantum versus mean-field collapse in a many-body system, Phys. Rev. A92, 043632 (2015)[abstract]

@ARTICLE{GEAstr-Quant-2015, author = {G. E. Astrakharchik and B. A. Malomed}, title = {Quantum versus mean-field collapse in a many-body system}, journal = {Phys. Rev. A}, volume = {92}, pages = {043632}, year = {2015} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik and B. A. Malomed TITULO: Quantum versus mean-field collapse in a many-body system REF REVISTA/LIBRO: Phys. Rev. A 92, 043632 CLAVE: A FECHA PUBLICACION (*): 2015

[22] G. Ferre, G. E. Astrakharchik, J. Boronat, Phase diagram of a quantum Coulomb wire, Phys. Rev. B92, 245305 (2015)[abstract]

@ARTICLE{GFerre,-Phase-2015, author = {G. Ferre and G. E. Astrakharchik and J. Boronat}, title = {Phase diagram of a quantum Coulomb wire}, journal = {Phys. Rev. B}, volume = {92}, pages = {245305}, year = {2015} }

AUTORES/AS (p.o. de firma): G. Ferre, G. E. Astrakharchik, J. Boronat TITULO: Phase diagram of a quantum Coulomb wire REF REVISTA/LIBRO: Phys. Rev. B 92, 245305 CLAVE: A FECHA PUBLICACION (*): 2015

[23] A. Macia, G. E. Astrakharchik, F. Mazzanti, S. Giorgini, J. Boronat, Single-particle versus pair superfluidity in a bilayer system of dipolar bosons, Phys. Rev. A90, 043623 (2014) [journal][abstract]

We consider the ground state of a bilayer system of dipolar bosons, where dipoles are oriented by an external field in the direction perpendicular to the parallel planes. Quantum Monte Carlo methods are used to calculate the ground-state energy, the one-body and two-body density matrix, and the superfluid response as a function of the separation between layers. We find that by decreasing the interlayer distance for fixed value of the strength of the dipolar interaction, the system undergoes a quantum phase transition from a single-particle to a pair superfluid. The single-particle superfluid is characterized by a finite value of both the atomic condensate and the super-counterfluid density. The pair superfluid phase is found to be stable against formation of many-body cluster states and features a gap in the spectrum of elementary excitations.

@ARTICLE{AMacia,-Singl-2014, author = {A. Macia and G. E. Astrakharchik and F. Mazzanti and S. Giorgini and J. Boronat}, title = {Single-particle versus pair superfluidity in a bilayer system of dipolar bosons}, journal = {Phys. Rev. A}, volume = {90}, pages = {043623}, year = {2014} }

AUTORES/AS (p.o. de firma): A. Macia, G. E. Astrakharchik, F. Mazzanti, S. Giorgini, J. Boronat TITULO: Single-particle versus pair superfluidity in a bilayer system of dipolar bosons REF REVISTA/LIBRO: Phys. Rev. A 90, 043623 CLAVE: A FECHA PUBLICACION (*): 2014

[24] G. E. Astrakharchik and J. Boronat, Luttinger liquid behavior of one-dimensional 3He, Phys. Rev. B90, 235439 (2014) [journal][abstract]

The ground-state properties of one-dimensional He3 are studied using quantum Monte Carlo methods. The equation of state is calculated in a wide range of physically relevant densities and is well interpolated by a power-series fit. The Luttinger liquid theory is found to describe the long-range properties of the correlation functions. The density dependence of the Luttinger parameter is explicitly found, and interestingly it shows a nonmonotonic behavior. Depending on the density, the static structure factor can be a smooth function of the momentum or might contain a peak of a finite or infinite height. Although no phase transitions are present in the system, we identify a number of physically different regimes, including an ideal Fermi gas, a “Bose gas.” a “super-Tonks-Girardeau” regime, and a “quasicrystal.” The obtained results are applicable to unpolarized, partially, or fully polarized He3.

AUTORES/AS (p.o. de firma): G. E. Astrakharchik and J. Boronat TITULO: Luttinger liquid behavior of one-dimensional 3He REF REVISTA/LIBRO: Phys. Rev. B 90, 235439 CLAVE: A FECHA PUBLICACION (*): 2014

[25] G. E. Astrakharchik, J. Boronat, E. Krotscheck, and T. Lichtenegger, Dynamic structure function of a cold Fermi gas at unitarity, J. Phys.: Conf. Ser.529, 012009 (2014) [journal][abstract]

We present a theoretical study of the dynamic structure function of a resonantly interacting two-component Fermi gas at zero temperature. Our approach is based on dynamic many-body theory able to describe excitations in strongly correlated Fermi systems. The fixed-node diffusion Monte Carlo method is used to produce the ground-state correlation functions which are used as an input for the excitation theory. Our approach reproduces recent Bragg scattering data in both the density and the spin channel. In the BCS regime, the response is close to that of the ideal Fermi gas. On the BEC side, the Bose peak associated with the formation of dimers dominates the density channel of the dynamic response. When the fraction of dimers is large our theory departs from the experimental data, mainly in the spin channel.

@ARTICLE{GEAstr-Dynam-2014, author = {G. E. Astrakharchik and J. Boronat and E. Krotscheck and T. Lichtenegger}, title = {Dynamic structure function of a cold Fermi gas at unitarity}, journal = {J. Phys.: Conf. Ser.}, volume = {529}, pages = {012009}, year = {2014} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, J. Boronat, E. Krotscheck, and T. Lichtenegger TITULO: Dynamic structure function of a cold Fermi gas at unitarity REF REVISTA/LIBRO: J. Phys.: Conf. Ser. 529, 012009 CLAVE: A FECHA PUBLICACION (*): 2014

[26] M. A. García-March, B. Juliá-Díaz, G. E. Astrakharchik, J. Boronat, A. Polls, Distinguishability, degeneracy, and correlations in three harmonically trapped bosons in one dimension, Phys. Rev. A90, 063605 (2014) [journal][abstract]

We study a system of two bosons of one species and a third atom of a second species in a one-dimensional parabolic trap at zero temperature. We assume contact repulsive inter- and intraspecies interactions. By means of an exact diagonalization method we calculate the ground and excited states for the whole range of interactions. We use discrete group theory to classify the eigenstates according to the symmetry of the interaction potential. We also propose and validate analytical Ansätze gaining physical insight over the numerically obtained wave functions. We show that, for both approaches, it is crucial to take into account that the distinguishability of the third atom implies the absence of any restriction over the wave function when interchanging this boson with any of the other two. We find that there are degeneracies in the spectra in some limiting regimes, that is, when the interspecies and/or the intraspecies interactions tend to infinity. This is in contrast with the three-identical boson system, where no degeneracy occurs in these limits. We show that, when tuning both types of interactions through a protocol that keeps them equal while they are increased towards infinity, the systems's ground state resembles that of three indistinguishable bosons. Contrarily, the systems's ground state is different from that of three-identical bosons when both types of interactions are increased towards infinity through protocols that do not restrict them to be equal. We study the coherence and correlations of the system as the interactions are tuned through different protocols, which permit us to build up different correlations in the system and lead to different spatial distributions of the three atoms.

@ARTICLE{MAGarc-Disti-2014, author = {M. A. García-March and B. Juliá-Díaz and G. E. Astrakharchik and J. Boronat and A. Polls}, title = {Distinguishability, degeneracy, and correlations in three harmonically trapped bosons in one dimension}, journal = {Phys. Rev. A}, volume = {90}, pages = {063605}, year = {2014} }

AUTORES/AS (p.o. de firma): M. A. García-March, B. Juliá-Díaz, G. E. Astrakharchik, J. Boronat, A. Polls TITULO: Distinguishability, degeneracy, and correlations in three harmonically trapped bosons in one dimension REF REVISTA/LIBRO: Phys. Rev. A 90, 063605 CLAVE: A FECHA PUBLICACION (*): 2014

[27] M. A. Garcia-March, B. Julia-Diaz, G. E. Astrakharchik, Th. Busch, J. Boronat, A. Polls, Quantum correlations and spatial localization in one-dimensional ultracold bosonic mixtures, New J. Phys.16, 103004 (2014) [journal][abstract]

We present the complete phase diagram for one-dimensional binary mixtures of bosonic ultracold atomic gases in a harmonic trap. We obtain exact results with direct numerical diagonalization for a small number of atoms, which permits us to quantify quantum many-body correlations. The quantum Monte Carlo method is used to calculate energies and density profiles for larger system sizes. We study the system properties for a wide range of interaction parameters. For the extreme values of these parameters, different correlation limits can be identified, where the correlations are either weak or strong. We investigate in detail how the correlations evolve between the limits. For balanced mixtures in the number of atoms in each species, the transition between the different limits involves sophisticated changes in the one- and two-body correlations. Particularly, we quantify the entanglement between the two components by means of the von Neumann entropy. We show that the limits equally exist when the number of atoms is increased for balanced mixtures. Also, the changes in the correlations along the transitions among these limits are qualitatively similar. We also show that, for imbalanced mixtures, the same limits with similar transitions exist. Finally, for strongly imbalanced systems, only two limits survive, i.e., a miscible limit and a phase-separated one, resembling those expected with a mean-field approach

@ARTICLE{MAGarc-Quant-2014, author = {M. A. Garcia-March and B. Julia-Diaz and G. E. Astrakharchik and Th. Busch and J. Boronat and A. Polls}, title = {Quantum correlations and spatial localization in one-dimensional ultracold bosonic mixtures}, journal = {New J. Phys.}, volume = {16}, pages = {103004}, year = {2014} }

AUTORES/AS (p.o. de firma): M. A. Garcia-March, B. Julia-Diaz, G. E. Astrakharchik, Th. Busch, J. Boronat, A. Polls TITULO: Quantum correlations and spatial localization in one-dimensional ultracold bosonic mixtures REF REVISTA/LIBRO: New J. Phys. 16, 103004 CLAVE: A FECHA PUBLICACION (*): 2014

[28] Y. Lutsyshyn, G. E. Astrakharchik, C. Cazorla, J. Boronat, Quantum phase transition with a simple variational ansatz, Phys. Rev. B90, 214512 (2014) [journal][abstract]

We study the zero-temperature quantum phase transition between liquid and hcp solid He4. We use the variational method with a simple yet exchange-symmetric and fully explicit wave function. It is found that the optimized wave function undergoes spontaneous symmetry breaking and describes the quantum solidification of helium at 22 atm. The explicit form of the wave function allows us to consider various contributions to the phase transition. We find that the employed wave function is an excellent candidate for describing both a first-order quantum phase transition and the ground state of a Bose solid.

@ARTICLE{YLutsysh-Quant-2014, author = {Y. Lutsyshyn and G. E. Astrakharchik and C. Cazorla and J. Boronat}, title = {Quantum phase transition with a simple variational ansatz}, journal = {Phys. Rev. B}, volume = {90}, pages = {214512}, year = {2014} }

AUTORES/AS (p.o. de firma): Y. Lutsyshyn, G. E. Astrakharchik, C. Cazorla, J. Boronat TITULO: Quantum phase transition with a simple variational ansatz REF REVISTA/LIBRO: Phys. Rev. B 90, 214512 CLAVE: A FECHA PUBLICACION (*): 2014

[29] Z. D. Zhang, G. E. Astrakharchik, D. C. Aveline, S. Choi, H. Perrin, T. H. Bergeman, M. Olshanii , Breakdown of the scale invariance in a near-Tonks-Girardeau gas: some exact results and beyond, Phys. Rev. A89, 063616 (2014) [journal][abstract]

monopole excitations harmonically trapped Bose gas in vicinity Tonks-Girardeau limit Using Girardeau's Fermi-Bose duality subsequently an effective fermion-fermion odd-wave interaction obtain dominant correction scale-invariance-protected excitation frequency microscopically excitation amplitudes produce series diffusion Monte Carlo results confirm our analytic prediction three particles And less expectedly our result stands in excellent agreement with result hydrodynamic simulation (with Lieb-Liniger equation state an input) microscopically large but macroscopically excitations also frequency obtain coincides with upper bound derived Menotti Stringari using sum rules Surprisingly however found usually successful hydrodynamic perturbation ory predicts shift 9/4 higher ab initio numerical counterpart conjecture sharp boundary cloud in local density approximation—characterized an infinite density gradient—renders perturbation inapplicable All our results also directly apply three-dimensional p-wave-interacting waveguide-confined fermions

@ARTICLE{ZDZhan-Break-2014, author = {Z. D. Zhang and G. E. Astrakharchik and D. C. Aveline and S. Choi and H. Perrin and T. H. Bergeman and M. Olshanii }, title = {Breakdown of the scale invariance in a near-Tonks-Girardeau gas: some exact results and beyond}, journal = {Phys. Rev. A}, volume = {89}, pages = {063616}, year = {2014} }

AUTORES/AS (p.o. de firma): Z. D. Zhang, G. E. Astrakharchik, D. C. Aveline, S. Choi, H. Perrin, T. H. Bergeman, M. Olshanii TITULO: Breakdown of the scale invariance in a near-Tonks-Girardeau gas: some exact results and beyond REF REVISTA/LIBRO: Phys. Rev. A 89, 063616 CLAVE: A FECHA PUBLICACION (*): 2014

[30] G. E. Astrakharchik and I. Brouzos, Trapped one-dimensional ideal
Fermi gas with a single impurity, Phys. Rev. A88, 021602(R) (2013) [journal][abstract]

Ground-state properties single impurity in one-dimensional Fermi gas investigated in uniform trapped geometries energy trapped system obtained (i) generalizing McGuire expression uniform trapped system (ii) within local density approximation (iii) using perturbative approach in case weakly interacting impurity (iv) diffusion Monte Carlo method demonstrate re closed formula based exact solution homogeneous case provides precise estimation energy trapped system even number fermions arbitrary coupling constant impurity Using expression analyze energy contributions kinetic interaction potential components well spatial properties such system size pair-correlation function Finally calculate frequency breathing mode Our analysis directly connected applicable recent experiments in microtraps

@ARTICLE{GEAstr-Trapp-2013, author = {G. E. Astrakharchik and I. Brouzos}, title = {Trapped one-dimensional ideal Fermi gas with a single impurity}, journal = {Phys. Rev. A}, volume = {88}, pages = {021602(R)}, year = {2013} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik and I. Brouzos TITULO: Trapped one-dimensional ideal
Fermi gas with a single impurity REF REVISTA/LIBRO: Phys. Rev. A 88, 021602(R) CLAVE: A FECHA PUBLICACION (*): 2013

[31] G. E. Astrakharchik and L. P. Pitaevskii, Lieb's soliton-like excitations in harmonic traps, EPL102, 30004 (2013) [journal][abstract]

solitonic Lieb II branch excitations in one-dimensional Bose gas in homogeneous trapped geometry Using Bethe-ansatz Lieb's equations calculate

@ARTICLE{GEAstr-Lieb'-2013, author = {G. E. Astrakharchik and L. P. Pitaevskii}, title = {Lieb's soliton-like excitations in harmonic traps}, journal = {EPL}, volume = {102}, pages = {30004}, year = {2013} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik and L. P. Pitaevskii TITULO: Lieb's soliton-like excitations in harmonic traps REF REVISTA/LIBRO: EPL 102, 30004 CLAVE: A FECHA PUBLICACION (*): 2013

[32] G. E. Astrakharchik, K.V. Krutitsky, and P. Navez, Phase diagram of quasi-two-dimensional bosons in laser speckle potential, Phys. Rev. A87, 061601(R) (2013) [journal][abstract]

phase diagram quasi-two-dimensional interacting Bose gas zero temperature in presence random potential created laser speckles superfluid fraction fraction particles with zero momentum obtained within mean-field Gross-Pitaevskii ory in diffusion Monte Carlo simulations transition superfluid insulating state when strength disorder grows Estimations critical parameters compared with predictions percolation ory in Thomas-Fermi approximation Analytical expressions zero-momentum fraction superfluid fraction derived in limit weak disorder weak interactions within framework Bogoliubov ory Limits validity various approximations discussed

@ARTICLE{GEAstr-Phase-2013, author = {G. E. Astrakharchik and K.V. Krutitsky and P. Navez}, title = {Phase diagram of quasi-two-dimensional bosons in laser speckle potential}, journal = {Phys. Rev. A}, volume = {87}, pages = {061601(R)}, year = {2013} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, K.V. Krutitsky, and P. Navez TITULO: Phase diagram of quasi-two-dimensional bosons in laser speckle potential REF REVISTA/LIBRO: Phys. Rev. A 87, 061601(R) CLAVE: A FECHA PUBLICACION (*): 2013

[33] M. A. Garcia-March, B. Julia-Diaz, G.E. Astrakharchik, Th. Busch, J.
Boronat, and A. Polls, Sharp crossover from composite fermionization to phase separation in mesoscopic mixtures of ultracold
bosons, Phys. Rev. A88, 063604 (2013) [journal][abstract]

two-component mixture few repulsively interacting ultracold atoms in one-dimensional trap possesses very diverse quantum regimes crossover between m can induced tuning interactions in species Starting composite fermionization regime in interactions between both components large neither gas phase coherent our results phase-separated state can reached increasing interaction in species In regime weakly interacting component stays center trap becomes almost fully phase coherent while strongly interacting expelled edges trap crossover sharp can witnessed in system's energy in occupation lowest natural orbital weakly interacting species such transition few-atom effect disappears large population imbalance

@ARTICLE{MAGarc-Sharp-2013, author = {M. A. Garcia-March and B. Julia-Diaz and G.E. Astrakharchik and Th. Busch and J.
Boronat and A. Polls}, title = {Sharp crossover from composite fermionization to phase separation in mesoscopic mixtures of ultracold bosons}, journal = {Phys. Rev. A}, volume = {88}, pages = {063604 }, year = {2013} }

AUTORES/AS (p.o. de firma): M. A. Garcia-March, B. Julia-Diaz, G.E. Astrakharchik, Th. Busch, J.
Boronat, and A. Polls TITULO: Sharp crossover from composite fermionization to phase separation in mesoscopic mixtures of ultracold
bosons REF REVISTA/LIBRO: Phys. Rev. A 88, 063604 CLAVE: A FECHA PUBLICACION (*): 2013

[34] G. E. Astrakharchik, S. Giorgini, and J. Boronat, Stability of resonantly interacting heavy-light Fermi mixtures, Phys. Rev. B86, 174518 (2012) [journal][abstract]

two-component mixture resonantly interacting Fermi gases function ratio κ heavy light mass species diffusion Monte Carlo method calculate ground-state energy pair correlation function starting guiding wave functions describe respectively superfluid normal state gas Results mixture stable superfluid mass ratios smaller critical κc=13±1 larger values κ simulations utilizing wave function normal state unstable cluster formation relevant cluster states driving instability formed light particle heavy particles within distances order range interatomic potential overlap between wave function trimer bound state guiding wave function describe superfluid state unphysical stability superfluid gas

@ARTICLE{GEAstr-Stabi-2012, author = {G. E. Astrakharchik and S. Giorgini and J. Boronat}, title = {Stability of resonantly interacting heavy-light Fermi mixtures}, journal = {Phys. Rev. B}, volume = {86}, pages = {174518}, year = {2012} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, S. Giorgini, and J. Boronat TITULO: Stability of resonantly interacting heavy-light Fermi mixtures REF REVISTA/LIBRO: Phys. Rev. B 86, 174518 CLAVE: A FECHA PUBLICACION (*): 2012

[35] M. D. Girardeau and G. E. Astrakharchik, Super-Tonks-Girardeau State in an Attractive One-Dimensional Dipolar Gas, Phys. Rev. Lett.109, 235305 (2012) [journal][abstract]

ground state one-dimensional (1D) quantum gas dipoles oriented perpendicular longitudinal axis with strong 1/x3 repulsive potential studied low 1D densities n Near contact dependence many-body wave function separation xjℓ particles reduces two-body wave function Ψrel(xjℓ) Immediately after sudden rotation dipoles so y parallel longitudinal axis wave function will still repulsive potential but since potential now attractive potential will not stationary It n nd2→0 rate change wave function approaches zero It follows values nd2 state metastable an analog super Tonks-Girardeau state bosons with strong zero-range attraction dipolar system equivalent spinor Fermi gas with spin z components σ↑=⊥ (perpendicular longitudinal axis) σ↓=∥ (parallel longitudinal axis) Fermi-Fermi mapping spinor spinless Fermi gas followed standard 1960 Fermi-Bose mapping reduces Fermi system Bose gas Potential experiments realizing sudden spin rotation with ultracold dipolar gases discussed few salient properties se states accurately evaluated Monte Carlo method

@ARTICLE{MDGira-Super-2012, author = {M. D. Girardeau and G. E. Astrakharchik}, title = {Super-Tonks-Girardeau State in an Attractive One-Dimensional Dipolar Gas}, journal = {Phys. Rev. Lett.}, volume = {109}, pages = {235305}, year = {2012} }

AUTORES/AS (p.o. de firma): M. D. Girardeau and G. E. Astrakharchik TITULO: Super-Tonks-Girardeau State in an Attractive One-Dimensional Dipolar Gas REF REVISTA/LIBRO: Phys. Rev. Lett. 109, 235305 CLAVE: A FECHA PUBLICACION (*): 2012

[36] O. N. Osychenko, G. E. Astrakharchik, F. Mazzanti, and J. Boronat, Zero-temperature phase diagram of Yukawa bosons, Phys. Rev. A85, 063604 (2012) [journal][abstract]

yukawa phase transition
study zero-temperature phase diagram bosons interacting via screened Coulomb (Yukawa) potential means diffusion Monte Carlo method Yukawa potential model interaction in neutron matter dusty plasmas charged colloids As n Petrov et al [Phys Rev Lett 99 130407 (2007)] interactions between weakly bound molecules heavy light fermionic atoms described an effective Yukawa potential with strength related heavy-light mass ratio M/m might lead crystallization in two-dimensional geometry if mass ratio heavy-light fermions exceeds certain critical In present work do thorough quantum three-dimensional Yukawa system strong interactions (equivalently large mass ratios) system experiences several phase transitions density increased passing gas solid gas phase again Weakly interacting Yukawa particles do not crystallize density minimal interaction strength crystallization happens In terms two-component fermionic system strength corresponds heavy-light mass ratio M/m∼180 so impossible realize gas-crystal transition in conventional bulk system Yukawa model fermionic mixtures also analyze possibility building molecular systems with very large effective mass ratios confining heavy component sufficiently deep optical lattice how effective mass heavy component can made arbitrarily large increasing lattice depth thus leading tunable effective mass ratio can realize molecular superlattice

@ARTICLE{ONOsyc-Zero--2012, author = {O. N. Osychenko and G. E. Astrakharchik and F. Mazzanti and J. Boronat}, title = {Zero-temperature phase diagram of Yukawa bosons}, journal = {Phys. Rev. A}, volume = {85}, pages = {063604}, year = {2012} }

AUTORES/AS (p.o. de firma): O. N. Osychenko, G. E. Astrakharchik, F. Mazzanti, and J. Boronat TITULO: Zero-temperature phase diagram of Yukawa bosons REF REVISTA/LIBRO: Phys. Rev. A 85, 063604 CLAVE: A FECHA PUBLICACION (*): 2012

[37] O. N. Osychenko, G. E. Astrakharchik, J. Boronat, Ewald method for polytropic potentials in arbitrary dimensionality, Molecular Physics
110, 227-247 (2012) [journal][abstract]

summation technique generalised power-law 1/|r|^k potentials in three- two- one-dimensional geometries with explicit formulae all components sums cases short-range long-range "marginal" interactions treated separately jellium model particular case charge-neutral system discussed explicit forms sums such system presented generalised form sums noncubic (nonsquare) simulation cell three- (two-) dimensional geometry obtained possible field application discussed procedure optimisation involved parameters in actual simulations developed an example application presented

@ARTICLE{ONOsyc-Ewald-2012, author = {O. N. Osychenko and G. E. Astrakharchik and J. Boronat}, title = {Ewald method for polytropic potentials in arbitrary dimensionality}, journal = {Molecular Physics
}, volume = {110}, pages = {227-247}, year = {2012} }

AUTORES/AS (p.o. de firma): O. N. Osychenko, G. E. Astrakharchik, J. Boronat TITULO: Ewald method for polytropic potentials in arbitrary dimensionality REF REVISTA/LIBRO: Molecular Physics
110, 227-247 CLAVE: A FECHA PUBLICACION (*): 2012

[38] A. E. Golomedov, G. E. Astrakharchik, and Yu. E. Lozovik, Mesoscopic supersolid of dipoles in a trap, Phys. Rev. A84, 033615 (2011) [journal][abstract]

A mesoscopic system of dipolar bosons trapped by a harmonic potential is considered. The system has a number of physical realizations including dipole excitons, atoms with large dipolar moment, polar molecules, and Rydberg atoms in inhomogeneous electric field. We carry out a diffusion Monte Carlo simulation to define the quantum properties of a two-dimensional system of trapped dipoles at zero temperature. In dimensionless units the system is described by two control parameters, namely, the number of particles and the strength of the interparticle interaction. We have shown that when the interparticle interaction is strong enough a mesoscopic crystal is formed. As the strength of interactions is decreased a multistage melting takes place. Off-diagonal order in the system is tested using natural-orbitals analysis. We have found that the system might be Bose condensed even in the case of strong interparticle interactions. There is a set of parameters for which a spatially ordered structure is formed while simultaneously the fraction of Bose-condensed particles is nonzero. This might be considered as a realization of a mesoscopic supersolid.

@ARTICLE{AEGolo-Mesos-2011, author = {A. E. Golomedov and G. E. Astrakharchik and Yu. E. Lozovik}, title = {Mesoscopic supersolid of dipoles in a trap}, journal = {Phys. Rev. A}, volume = {84}, pages = {033615}, year = {2011} }

AUTORES/AS (p.o. de firma): A. E. Golomedov, G. E. Astrakharchik, and Yu. E. Lozovik TITULO: Mesoscopic supersolid of dipoles in a trap REF REVISTA/LIBRO: Phys. Rev. A 84, 033615 CLAVE: A FECHA PUBLICACION (*): 2011

[39] G. E. Astrakharchik and K. V. Krutitsky, Condensate fraction in
non-uniform systems, Phys. Rev. A84, 031604(R) (2011) [journal][abstract]

Exact calculation condensate fraction in multidimensional inhomogeneous interacting Bose systems in confining potential arbitrary shape difficult computational problem have developed an iterative procedure allows us calculate condensate fraction well corresponding eigenfunction one-body density matrix successfully validate procedure in diffusion Monte Carlo simulations Bose gas in an optical lattice zero temperature also discuss relation between criteria testing coherence in cold Bose systems such fraction particles superfluid condensed in zero-momentum state

@ARTICLE{GEAstr-Conde-2011, author = {G. E. Astrakharchik and K. V. Krutitsky}, title = {Condensate fraction in non-uniform systems}, journal = {Phys. Rev. A}, volume = {84}, pages = {031604(R)}, year = {2011} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik and K. V. Krutitsky TITULO: Condensate fraction in
non-uniform systems REF REVISTA/LIBRO: Phys. Rev. A 84, 031604(R) CLAVE: A FECHA PUBLICACION (*): 2011

[40] G. E. Astrakharchik and M. D. Girardeau, Exact ground state properties of the one-dimensional Coulomb gas, Phys. Rev. B83, 153303 (2011) [journal][abstract]

ground-state properties single-component one-dimensional Coulomb gas investigated use Bose-Fermi mapping ground-state wave function permits solution Fermi sign problem in following respects (i) nodal surface known permitting exact calculations; (ii) evaluation determinants avoided reducing numerical complexity bosonic system thus allowing simulation large number fermions Due mapping energy local properties in one-dimensional Coulomb systems exactly same Bose-Einstein Fermi-Dirac statistics exact ground-state energy calculated in homogeneous trapped geometries using diffusion Monte Carlo method in low-density Wigner crystal limit an elementary low-lying excitation plasmon contrasted with high-density ideal Fermi gas/Tonks-Girardeau limit where low-lying excitations phonons Exact density profiles compared ones calculated within local density approximation predicts change semicircular an inverted parabolic shape density profile charge increased

@ARTICLE{GEAstr-Exact-2011, author = {G. E. Astrakharchik and M. D. Girardeau}, title = {Exact ground state properties of the one-dimensional Coulomb gas}, journal = {Phys. Rev. B}, volume = {83}, pages = {153303}, year = {2011} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik and M. D. Girardeau TITULO: Exact ground state properties of the one-dimensional Coulomb gas REF REVISTA/LIBRO: Phys. Rev. B 83, 153303 CLAVE: A FECHA PUBLICACION (*): 2011

[41] G. E. Astrakharchik and N. A. Astrakharchik, Numerical study of Kapitza pendulum, arXiv:1103.5981 (2011) [journal][abstract]

driven pendulum with vertical oscillations pendulum support (Kapitza pendulum) possesses number unusual properties popular object both analytical numerical studies Although spectacular results can obtained such vertical position pendulum under certain conditions might become stable no explicit analytical solution pendulum trajectory known carry out numerical Kapitza pendulum number physical regimes Comparison made with limiting cases where exact solution known

@ARTICLE{GEAstr-Numer-2011, author = {G. E. Astrakharchik and N. A. Astrakharchik}, title = {Numerical study of Kapitza pendulum}, journal = {arXiv:1103.5981}, year = {2011} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik and N. A. Astrakharchik TITULO: Numerical study of Kapitza pendulum REF REVISTA/LIBRO: arXiv:1103.5981 , CLAVE: A FECHA PUBLICACION (*): 2011

[42] O. N. Osychenko, G. E. Astrakharchik, Y. Lutsyshyn, Yu. E. Lozovik,
and J. Boronat, Phase diagram of Rydberg atoms with repulsive van der Waals interaction, Phys. Rev. A84, 063621 (2011) [journal][abstract]

rydberg
report quantum Monte Carlo calculation phase diagram bosons interacting with repulsive inverse sixth power pair potential model assemblies Rydberg atoms in local van der Waals blockade regime model can parametrized in terms just parameters reduced density temperature Solidification happens fcc phase At zero temperature transition density found with diffusion Monte Carlo method density ρ=3 9(ℏ2/mC6)3/4 where C6 strength interaction solidification curve nonzero temperature studied with path-integral Monte Carlo approach compared with transitions in corresponding harmonic classical crystals Relaxation mechanisms considered in relation present experiments

@ARTICLE{ONOsyc-Phase-2011, author = {O. N. Osychenko and G. E. Astrakharchik and Y. Lutsyshyn and Yu. E. Lozovik and
and J. Boronat}, title = {Phase diagram of Rydberg atoms with repulsive van der Waals interaction}, journal = {Phys. Rev. A}, volume = {84}, pages = {063621}, year = {2011} }

AUTORES/AS (p.o. de firma): O. N. Osychenko, G. E. Astrakharchik, Y. Lutsyshyn, Yu. E. Lozovik,
and J. Boronat TITULO: Phase diagram of Rydberg atoms with repulsive van der Waals interaction REF REVISTA/LIBRO: Phys. Rev. A 84, 063621 CLAVE: A FECHA PUBLICACION (*): 2011

[43] C. Cazorla, G. E. Astrakharchik, J. Casulleras, J. Boronat, Ground-state properties and superfluidity of two- and quasi-two-dimensional solid 4He, J. Phys.: Condens. Matter22, 165402 (2010) [journal][abstract]

In a recent study we have reported a new type of trial wavefunction symmetric under the exchange of particles, which is able to describe a supersolid phase. In this work, we use the diffusion Monte Carlo method and this model wavefunction to study the properties of solid 4He in two- and quasi-two-dimensional geometries. In the purely two-dimensional (2D) case, we obtain results for the total ground-state energy and freezing and melting densities which are in good agreement with previous exact Monte Carlo calculations performed with a slightly different interatomic potential model. We calculate the value of the zero-temperature superfluid fraction ρs/ρ of 2D solid 4He and find that it is negligible in all the considered cases, similarly to what is obtained in the perfect (free of defects) three-dimensional crystal using the same computational approach. Interestingly, by allowing the atoms to move locally in the direction perpendicular to the plane where they are confined to zero-point oscillations (quasi-2D crystal), we observe the emergence of a finite superfluid density that coexists with the periodicity of the system.

@ARTICLE{CCazorla-Groun-2010, author = {C. Cazorla and G. E. Astrakharchik and J. Casulleras and J. Boronat}, title = {Ground-state properties and superfluidity of two- and quasi-two-dimensional solid 4He}, journal = {J. Phys.: Condens. Matter}, volume = {22}, pages = {165402}, year = {2010} }

AUTORES/AS (p.o. de firma): C. Cazorla, G. E. Astrakharchik, J. Casulleras, J. Boronat TITULO: Ground-state properties and superfluidity of two- and quasi-two-dimensional solid 4He REF REVISTA/LIBRO: J. Phys.: Condens. Matter 22, 165402 CLAVE: A FECHA PUBLICACION (*): 2010

[44] G. E. Astrakharchik, J. Boronat, I. L. Kurbakov, Yu. E. Lozovik, and F. Mazzanti, Low-dimensional weakly interacting Bose gases: Nonuniversal equations of state, Phys. Rev. A81, 013612 (2010) [journal][abstract]

zero-temperature equation state analyzed in low-dimensional bosonic systems propose use concept energy-dependent s-wave scattering length obtaining estimations nonuniversal terms in energy expansion test approach making comparison exactly solvable one-dimensional problems generated terms have correct structure applicability two-dimensional systems analyzed comparing with results Monte Carlo simulations prediction nonuniversal behavior qualitatively correct densities deviations universal equation state become visible estimated properly Finally possibility observing nonuniversal terms in experiments with trapped gases also discussed

@ARTICLE{GEAstr-Low-d-2010, author = {G. E. Astrakharchik and J. Boronat and I. L. Kurbakov and Yu. E. Lozovik and F. Mazzanti}, title = {Low-dimensional weakly interacting Bose gases: Nonuniversal equations of state}, journal = {Phys. Rev. A}, volume = {81}, pages = {013612}, year = {2010} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, J. Boronat, I. L. Kurbakov, Yu. E. Lozovik, and F. Mazzanti TITULO: Low-dimensional weakly interacting Bose gases: Nonuniversal equations of state REF REVISTA/LIBRO: Phys. Rev. A 81, 013612 CLAVE: A FECHA PUBLICACION (*): 2010

[45] I. L. Kurbakov, Yu. E. Lozovik, G. E. Astrakharchik, and J. Boronat, Quasiequilibrium supersolid phase of a two-dimensional dipolar crystal, Phys. Rev. B82, 014508 (2010) [journal][abstract]

have studied possible existence supersolid phase two-dimensional dipolar crystal using quantum-Monte Carlo methods zero temperature Our results commensurate solid not supersolid in rmodynamic limit presence vacancies interstitials turns solid into supersolid phase even when tiny fraction m present in macroscopic system effective interaction between vacancies repulsive making quasiequilibrium dipolar supersolid possible

@ARTICLE{ILKurb-Quasi-2010, author = {I. L. Kurbakov and Yu. E. Lozovik and G. E. Astrakharchik and J. Boronat}, title = {Quasiequilibrium supersolid phase of a two-dimensional dipolar crystal}, journal = {Phys. Rev. B}, volume = {82}, pages = {014508}, year = {2010} }

AUTORES/AS (p.o. de firma): I. L. Kurbakov, Yu. E. Lozovik, G. E. Astrakharchik, and J. Boronat TITULO: Quasiequilibrium supersolid phase of a two-dimensional dipolar crystal REF REVISTA/LIBRO: Phys. Rev. B 82, 014508 CLAVE: A FECHA PUBLICACION (*): 2010

[46] M. D. Girardeau and G. E. Astrakharchik, Wave functions of the super-Tonks-Girardeau gas and the trapped one-dimensional hard-sphere Bose gas, Phys. Rev. A81, 061601(R) (2010) [journal][abstract]

Recent oretical experimental results demonstrate close connection between super-Tonks-Girardeau (STG) gas one-dimensional (1D) hard-sphere Bose (HSB) gas with hard-sphere diameter nearly equal 1D scattering length a1D STG gas highly excited gaslike state with nodes only interparticle separations ∣∣xjℓ∣∣=xnode≈a1D It n herein when coupling constant gB in Lieb-Liniger interaction gBδ(xjℓ) negative |x12|⩾xnode STG HSB wave functions N=2 particles not merely similar but identical; only difference between STG HSB wave functions STG wave function allows penetration into region |x12|2 STG HSB wave functions N=2 given exactly in terms parabolic cylinder function N⩾2 xnode given accurately simple parabola metastability STG phase generated sudden change coupling constant large positive large negative values explained in terms very overlap between ground state Tonks-Girardeau gas collapsed cluster states

@ARTICLE{MDGira-Wave-2010, author = {M. D. Girardeau and G. E. Astrakharchik}, title = {Wave functions of the super-Tonks-Girardeau gas and the trapped one-dimensional hard-sphere Bose gas}, journal = {Phys. Rev. A}, volume = {81}, pages = {061601(R)}, year = {2010} }

AUTORES/AS (p.o. de firma): M. D. Girardeau and G. E. Astrakharchik TITULO: Wave functions of the super-Tonks-Girardeau gas and the trapped one-dimensional hard-sphere Bose gas REF REVISTA/LIBRO: Phys. Rev. A 81, 061601(R) CLAVE: A FECHA PUBLICACION (*): 2010

[47] M. D. Girardeau and G.E. Astrakharchik, Ground state of a mixture of two bosonic Calogero-Sutherland gases with strong odd-wave interspecies attraction, Phys. Rev. A81, 043601 (2010) [journal][abstract]

model Calogero-Sutherland Bose gases B with strong odd-wave AB attractions induced p-wave AB Feshbach resonance studied ground-state wave function found analytically Bose-Bose duality mapping permits accurately determine static physical properties Monte Carlo method condensation particles particle pairs (molecules) tested analyzing presence off-diagonal long-range order in one- two- body density matrices p-wave symmetry AB interaction makes possible quasicondensation type particles Fermi momentum B component zero-temperature phase diagram drawn in terms densities interaction strengths

@ARTICLE{MDGira-Groun-2010, author = {M. D. Girardeau and G.E. Astrakharchik}, title = {Ground state of a mixture of two bosonic Calogero-Sutherland gases with strong odd-wave interspecies attraction}, journal = {Phys. Rev. A}, volume = {81}, pages = {043601}, year = {2010} }

AUTORES/AS (p.o. de firma): M. D. Girardeau and G.E. Astrakharchik TITULO: Ground state of a mixture of two bosonic Calogero-Sutherland gases with strong odd-wave interspecies attraction REF REVISTA/LIBRO: Phys. Rev. A 81, 043601 CLAVE: A FECHA PUBLICACION (*): 2010

[48] Y. Lutsyshyn, C. Cazorla, G. E. Astrakharchik, and J. Boronat, Properties of vacancy formation in hcp 4He crystals at zero temperature and fixed pressure, Phys. Rev. B82, 180506(R) (2010) [journal][abstract]

Equation state H4e hcp crystals with vacancies determined zero temperature using diffusion Monte Carlo technique an exact ground-state zero-temperature method This allows us extract formation enthalpy isobaric formation energy single vacancy in otherwise perfect helium solid Results obtained pressures up 160 bar isobaric formation energy found reach minimum near 57 bar where equal 10 5±1 2 K At same pressure vacancy formation volume exhibits maximum reaches volume unit cell This pressure coincides with pressure interval over peak in supersolid fraction H4e was observed in recent experiment

@ARTICLE{YLutsysh-Prope-2010, author = {Y. Lutsyshyn and C. Cazorla and G. E. Astrakharchik and J. Boronat}, title = {Properties of vacancy formation in hcp 4He crystals at zero temperature and fixed pressure}, journal = {Phys. Rev. B}, volume = {82}, pages = {180506(R)}, year = {2010} }

AUTORES/AS (p.o. de firma): Y. Lutsyshyn, C. Cazorla, G. E. Astrakharchik, and J. Boronat TITULO: Properties of vacancy formation in hcp 4He crystals at zero temperature and fixed pressure REF REVISTA/LIBRO: Phys. Rev. B 82, 180506(R) CLAVE: A FECHA PUBLICACION (*): 2010

[49] C. Cazorla, G. E. Astrakharchik, J. Casulleras, and J.
Boronat, Bose-Einstein Quantum Statistics and the Ground State of Solid 4He, New J. Phys.11, 013047 (2009) [journal][abstract]

The ground state of solid 4He is studied using the diffusion Monte Carlo method and a new trial wave function able to describe the supersolid. This wave function is symmetric under the exchange of particles and used as a guiding function in the method allows for reproducing the experimental equation of state. The use of this zero-temperature technique overcomes the conceptual ambiguity of finite-temperature methods in the search of a supersolid. Results for the one-body density matrix show the existence of off-diagonal long-range order with a very small condensate fraction ~ 10-4, the specific value being not fully independent of the trial wave function due to the remaining bias in the extrapolated estimator. The superfluid density of the commensurate system is below our resolution threshold, ρs/ρ< 10-5. This zero-temperature result is incompatible with recent experimental measures of superfluidity in solid 4He showing that the origin of the experimental findings is not that of a supersolid in a perfect crystal. Introducing in the system a 1% concentration of vacancies the superfluid density is manifestly larger, ρs/ρ=3.2(1)×10-3.

@ARTICLE{CCazorla-Bose--2009, author = {C. Cazorla and G. E. Astrakharchik and J. Casulleras and J.
Boronat}, title = {Bose-Einstein Quantum Statistics and the Ground State of Solid 4He}, journal = {New J. Phys.}, volume = {11}, pages = {013047}, year = {2009} }

AUTORES/AS (p.o. de firma): C. Cazorla, G. E. Astrakharchik, J. Casulleras, and J.
Boronat TITULO: Bose-Einstein Quantum Statistics and the Ground State of Solid 4He REF REVISTA/LIBRO: New J. Phys. 11, 013047 CLAVE: A FECHA PUBLICACION (*): 2009

[50] G. E. Astrakharchik, G. De Chiara, Giovanna Morigi, and J. Boronat, Thermal and quantum fluctuations in low dimensional dipolar chains, J. Phys. B: At. Mol. Opt. Phys.42, 154026 (2009) [journal][abstract]

Ultracold polar molecules in highly anisotropic traps interacting via repulsive dipolar potential may form one-dimensional chains high densities According classical ory low temperatures re exists critical density second order phase transition linear zigzag chain occurs effect rmal quantum fluctuations se self-organized structures using classical quantum Monte Carlo methods means evaluate pair correlation function static structure factor Depending parameters se functions exhibit properties typical crystalline liquid system compare rmal quantum results identifying analogies differences Finally discuss experimental parameter regimes where effects quantum fluctuations linear - zigzag transition can observed

@ARTICLE{GEAstr-Therm-2009, author = {G. E. Astrakharchik and G. De Chiara and Giovanna Morigi and J. Boronat}, title = {Thermal and quantum fluctuations in low dimensional dipolar chains}, journal = {J. Phys. B: At. Mol. Opt. Phys.}, volume = {42}, pages = {154026}, year = {2009} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, G. De Chiara, Giovanna Morigi, and J. Boronat TITULO: Thermal and quantum fluctuations in low dimensional dipolar chains REF REVISTA/LIBRO: J. Phys. B: At. Mol. Opt. Phys. 42, 154026 CLAVE: A FECHA PUBLICACION (*): 2009

[51] G. E. Astrakharchik, Giovanna Morigi, Gabriele De Chiara, and J.
Boronat, Ground state of low dimensional dipolar gases: linear, zigzag
and multiple chains, Virtual Journal of Nanoscale Science &
Technology19, Issue 2 Jan (2009)[abstract]

study ground-state phase diagram ultracold dipolar gases in highly anisotropic traps Starting one-dimensional geometry ramping down transverse confinement along direction gas reaches various planar distributions dipoles At large linear densities when dipolar gas exhibits crystal-like phase critical values transverse frequency exist configuration exhibits transverse patterns se critical values found means classical ory in full agreement with classical Monte Carlo simulations quantum system performed numerically with Monte Carlo techniques s quantum fluctuations smoothen transition make completely disappear in gas phase se predictions could experimentally tested would allow reveal effect zero-point motion self-organized mesoscopic structures matter waves such transverse pattern zigzag chain

@ARTICLE{GEAstr-Groun-2009, author = {G. E. Astrakharchik and Giovanna Morigi and Gabriele De Chiara and J.
Boronat}, title = {Ground state of low dimensional dipolar gases: linear, zigzag and multiple chains}, journal = {Virtual Journal of Nanoscale Science &
Technology}, volume = {19}, pages = {Issue 2 Jan}, year = {2009} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, Giovanna Morigi, Gabriele De Chiara, and J.
Boronat TITULO: Ground state of low dimensional dipolar gases: linear, zigzag
and multiple chains REF REVISTA/LIBRO: Virtual Journal of Nanoscale Science &
Technology 19, Issue 2 Jan CLAVE: A FECHA PUBLICACION (*): 2009

[52] G. E. Astrakharchik, J. Boronat, J. Casulleras, I. L. Kurbakov, and
Yu. E. Lozovik, Equation of state of a weakly interacting
two-dimensional Bose gas studied at zero temperature by means of quantum Monte Carlo methods, Phys. Rev. A79, 051602(R) (2009) [journal][abstract]

equation state weakly interacting two-dimensional Bose gas studied zero temperature means quantum Monte Carlo methods Going down low densities na2∝10−100 permits us obtain agreement beyond mean-field level between predictions perturbative methods direct many-body numerical simulation thus providing an answer fundamental question equation state two-dimensional dilute Bose gas in universal regime (i e entirely described gas parameter na2) also measure frequency breathing collective oscillation in trap very low densities can test universal equation state two-dimensional Bose gas

@ARTICLE{GEAstr-Equat-2009, author = {G. E. Astrakharchik and J. Boronat and J. Casulleras and I. L. Kurbakov and
Yu. E. Lozovik}, title = {Equation of state of a weakly interacting two-dimensional Bose gas studied at zero temperature by means of quantum Monte Carlo methods}, journal = {Phys. Rev. A}, volume = {79}, pages = {051602(R)}, year = {2009} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, J. Boronat, J. Casulleras, I. L. Kurbakov, and
Yu. E. Lozovik TITULO: Equation of state of a weakly interacting
two-dimensional Bose gas studied at zero temperature by means of quantum Monte Carlo methods REF REVISTA/LIBRO: Phys. Rev. A 79, 051602(R) CLAVE: A FECHA PUBLICACION (*): 2009

[53] D. Petrov, G.E. Astrakharchik, D. Papoular, C. Salomon, and G.V.
Shlyapnikov, Crystalline phase of strongly interacting Fermi mixtures, Recent Progress in Many Body Theories, Proceedings of the Fourteenth International Conference, edited J. Boronat, G. E. Astrakharchik and F. Mazzanti, (World Scientific, Singapore 94 (2008) [journal][abstract]

We show that the system of weakly bound molecules of heavy and light fermionic atoms is characterized by a long-range intermolecular repulsion and can undergo a gas-crystal quantum transition if the mass ratio exceeds a critical value. For the critical mass ratio above 100 obtained in our calculations, this crystalline order can be observed as a superlattice in an optical lattice for heavy atoms with a small filling factor. We also find that this novel system is sufficiently stable with respect to molecular relaxation into deep bound states and to the process of trimer formation.

@ARTICLE{DPetrov,-Cryst-2008, author = {D. Petrov and G.E. Astrakharchik and D. Papoular and C. Salomon and G.V.
Shlyapnikov}, title = {Crystalline phase of strongly interacting Fermi mixtures}, journal = {Recent Progress in Many Body Theories, Proceedings of the Fourteenth International Conference, edited J. Boronat, G. E. Astrakharchik and F. Mazzanti, (World Scientific, Singapore}, pages = {94}, year = {2008} }

AUTORES/AS (p.o. de firma): D. Petrov, G.E. Astrakharchik, D. Papoular, C. Salomon, and G.V.
Shlyapnikov TITULO: Crystalline phase of strongly interacting Fermi mixtures REF REVISTA/LIBRO: Recent Progress in Many Body Theories, Proceedings of the Fourteenth International Conference, edited J. Boronat, G. E. Astrakharchik and F. Mazzanti, (World Scientific, Singapore , 94 CLAVE: A FECHA PUBLICACION (*): 2008

[54] F. Mazzanti, G. E. Astrakharchik, J. Boronat, and J. Casulleras, Off-diagonal ground-state properties of a one-dimensional gas of Fermi hard rods, Phys. Rev. A77, 043632 (2008) [journal][abstract]

variational Monte Carlo calculation one-body density matrix momentum distribution system Fermi hard rods (HRs) presented compared with same quantities bosonic counterpart calculation exact within statistical errors since sample exact ground-state wave function whose analytical expression known numerical results in good agreement with known asymptotic expansions valid Luttinger liquids difference between absolute bosonic fermionic density matrices becomes marginally density increases In same regime corresponding momentum distributions merge into common profile independent statistics Nonanalytical contributions one-body density matrix also discussed found less relevant with increasing density

@ARTICLE{FMazzant-Off-d-2008, author = {F. Mazzanti and G. E. Astrakharchik and J. Boronat and J. Casulleras}, title = {Off-diagonal ground-state properties of a one-dimensional gas of Fermi hard rods}, journal = {Phys. Rev. A}, volume = {77}, pages = {043632}, year = {2008} }

AUTORES/AS (p.o. de firma): F. Mazzanti, G. E. Astrakharchik, J. Boronat, and J. Casulleras TITULO: Off-diagonal ground-state properties of a one-dimensional gas of Fermi hard rods REF REVISTA/LIBRO: Phys. Rev. A 77, 043632 CLAVE: A FECHA PUBLICACION (*): 2008

[55] F. Mazzanti, G.E. Astrakharchik, J.Boronat, and J.
Casulleras, Ground-state properties of a one-dimensional system of Hard Rods, Phys. Rev. Lett.100, 020401 (2008) [journal][abstract]

A quantum Monte Carlo simulation of a system of bosonic hard rods in one dimension is presented and discussed. The calculation is exact since the analytical form of the wave function is known and is in excellent agreement with predictions obtained from asymptotic expansions valid at large distances. The analysis of the static structure factor and the pair distribution function indicates that a solidlike and a gaslike phases exist at high and low densities, respectively. The one-body density matrix decays following a power law at large distances and produces a divergence in the low density momentum distribution at k=0 which can be identified as a quasicondensate.

@ARTICLE{FMazzant-Groun-2008, author = {F. Mazzanti and G.E. Astrakharchik and J.Boronat and J.
Casulleras}, title = {Ground-state properties of a one-dimensional system of Hard Rods}, journal = {Phys. Rev. Lett.}, volume = {100}, pages = {020401}, year = {2008} }

AUTORES/AS (p.o. de firma): F. Mazzanti, G.E. Astrakharchik, J.Boronat, and J.
Casulleras TITULO: Ground-state properties of a one-dimensional system of Hard Rods REF REVISTA/LIBRO: Phys. Rev. Lett. 100, 020401 CLAVE: A FECHA PUBLICACION (*): 2008

[56] F. Mazzanti, G.E. Astrakharchik, J.Boronat, and J. Casulleras, Static properties of a system of Bose hard rods in one-dimension, Proceedings of the Fourteenth International Conference, edited J. Boronat, G. E. Astrakharchik and F. Mazzanti (World Scientific, Singapore) 116 (2008) [journal][abstract]

We study the groundstate properties of a system of Bose Hard Rods of length a in one dimension by means of a Monte Carlo simulation. Since the analytical expression of the ground state wavefunction is known, the result of the calculation is exact. We discuss the behaviour of the static structure factor S(k), the pair distribution function g(z) and the momentum distribution n(k), and compare them to existing asymptotic expansions valid for Luttinger liquids at large distances.6 The analysis of S(k) reveals that two completely different regimes exist, characteristic of a solid-like (high density) and a gas-like (low density) phases. Furthermore, exact analytical values for S(k) at the momenta kj = 2πnj/a with n the density and j an integer, are derived. The one-body density matrix presents a power-law decay at large distances that turns into a divergent behaviour in n(k → 0) for densities lower than a critical value , thus stressing the presence of a Bose quasi-condensate.

@ARTICLE{FMazzant-Stati-2008, author = {F. Mazzanti and G.E. Astrakharchik and J.Boronat and J. Casulleras}, title = {Static properties of a system of Bose hard rods in one-dimension}, journal = {Proceedings of the Fourteenth International Conference, edited J. Boronat, G. E. Astrakharchik and F. Mazzanti (World Scientific, Singapore)}, pages = {116}, year = {2008} }

AUTORES/AS (p.o. de firma): F. Mazzanti, G.E. Astrakharchik, J.Boronat, and J. Casulleras TITULO: Static properties of a system of Bose hard rods in one-dimension REF REVISTA/LIBRO: Proceedings of the Fourteenth International Conference, edited J. Boronat, G. E. Astrakharchik and F. Mazzanti (World Scientific, Singapore) , 116 CLAVE: A FECHA PUBLICACION (*): 2008

[57] G. E. Astrakharchik and Yu. E. Lozovik, Super-Tonks-Girardeau regime in trapped one-dimensional dipolar gases , Phys. Rev. A77, 013404 (2008) [journal][abstract]

Possible signatures discussed super-Tonks-Girardeau gas in bosonic systems trapped quasi-one-dimensional dipoles zero temperature provide an estimation frequency lowest compressional mode compare analytical results derived using harmonic approach in high-density regime construct an exact mapping ground-state wave function one-dimensional dipolar system bosons fermions Bose-Fermi mixture conclude local properties energy same zero temperature question what extent dipolar potential can treated long short range discussed

AUTORES/AS (p.o. de firma): G. E. Astrakharchik and Yu. E. Lozovik TITULO: Super-Tonks-Girardeau regime in trapped one-dimensional dipolar gases REF REVISTA/LIBRO: Phys. Rev. A 77, 013404 CLAVE: A FECHA PUBLICACION (*): 2008

[58] G. E. Astrakharchik, Giovanna Morigi, Gabriele De Chiara, and J.
Boronat, Ground state of low-dimensional dipolar gases: Linear and zigzag chains, Phys. Rev. A78, 063622 (2008) [journal][abstract]

study ground-state phase diagram ultracold dipolar gases in highly anisotropic traps Starting one-dimensional geometry ramping down transverse confinement along direction gas reaches various planar distributions dipoles At large linear densities when dipolar gas exhibits crystal-like phase critical values transverse frequency exist configuration exhibits transverse patterns se critical values found means classical ory in full agreement with classical Monte Carlo simulations quantum system performed numerically with Monte Carlo techniques s quantum fluctuations smoothen transition make completely disappear in gas phase se predictions could experimentally tested would allow reveal effect zero-point motion self-organized mesoscopic structures matter waves such transverse pattern zigzag chain

@ARTICLE{GEAstr-Groun-2008, author = {G. E. Astrakharchik and Giovanna Morigi and Gabriele De Chiara and J.
Boronat}, title = {Ground state of low-dimensional dipolar gases: Linear and zigzag chains}, journal = {Phys. Rev. A}, volume = {78}, pages = {063622}, year = {2008} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, Giovanna Morigi, Gabriele De Chiara, and J.
Boronat TITULO: Ground state of low-dimensional dipolar gases: Linear and zigzag chains REF REVISTA/LIBRO: Phys. Rev. A 78, 063622 CLAVE: A FECHA PUBLICACION (*): 2008

[59] G. E. Astrakharchik, J. Boronat, J. Casulleras, I. L. Kurbakov, and
Yu. E. Lozovik, Ground state properties of a homogeneous 2D system of Bosons with dipolar interactions, Recent Progress in Many Body Theories, Proceedings of the Fourteenth International Conference, edited J. Boronat, G. E. Astrakharchik and F. Mazzanti, (World Scientific, Singapore, 2008 245 (2008) [journal][abstract]

The ground-state phase properties of a two-dimensional Bose system with dipole-dipole interactions is studied by means of quantum Monte Carlo techniques. Limitations of mean-field theory in a two-dimensional geometry are discussed. A quantum phase transition from gas to solid is found. The crystal is tested for the existence of a supersolid in the vicinity of the phase transition. The mesoscopic analogue of the off-diagonal long-range order is shown in the one-body density matrix in a finite-size crystal. A non-zero superfluid fraction is found in a finite-size crystal, the signal increasing dramatically in presence of vacancies.

@ARTICLE{GEAstr-Groun-2008, author = {G. E. Astrakharchik and J. Boronat and J. Casulleras and I. L. Kurbakov and
Yu. E. Lozovik}, title = {Ground state properties of a homogeneous 2D system of Bosons with dipolar interactions}, journal = {Recent Progress in Many Body Theories, Proceedings of the Fourteenth International Conference, edited J. Boronat, G. E. Astrakharchik and F. Mazzanti, (World Scientific, Singapore, 2008}, pages = {245}, year = {2008} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, J. Boronat, J. Casulleras, I. L. Kurbakov, and
Yu. E. Lozovik TITULO: Ground state properties of a homogeneous 2D system of Bosons with dipolar interactions REF REVISTA/LIBRO: Recent Progress in Many Body Theories, Proceedings of the Fourteenth International Conference, edited J. Boronat, G. E. Astrakharchik and F. Mazzanti, (World Scientific, Singapore, 2008 , 245 CLAVE: A FECHA PUBLICACION (*): 2008

[60] Yu. E. Lozovik, I. L. Kurbakov, G. E. Astrakharchik, M. Willander, Bose condensation of two-dimensional dipolar excitons: Simulation by the quantum Monte Carlo method, JETP106, 296 (2008) [journal][abstract]

The Bose condensation of two-dimensional dipolar excitons in quantum wells is numerically studied by the diffusion Monte Carlo simulation method. The correlation, microscopic, thermodynamic, and spectral characteristics are calculated. It is shown that, in structures of coupled quantum wells, in which low-temperature features of exciton luminescence have presently been observed, dipolar excitons form a strongly correlated system.

@ARTICLE{YuELoz-Bose-2008, author = {Yu. E. Lozovik and I. L. Kurbakov and G. E. Astrakharchik and M. Willander}, title = {Bose condensation of two-dimensional dipolar excitons: Simulation by the quantum Monte Carlo method}, journal = {JETP}, volume = {106}, pages = {296}, year = {2008} }

AUTORES/AS (p.o. de firma): Yu. E. Lozovik, I. L. Kurbakov, G. E. Astrakharchik, M. Willander TITULO: Bose condensation of two-dimensional dipolar excitons: Simulation by the quantum Monte Carlo method REF REVISTA/LIBRO: JETP 106, 296 CLAVE: A FECHA PUBLICACION (*): 2008

[61] ) Bo Zhao, Zeng-Bing Chen, Jian-Wei Pan, Jörg Schmiedmayer, Alessio Recati, Grigory E. Astrakharchik, and Tommaso Calarco, High-fidelity entanglement via molecular dissociation in integrated atom optics, Phys. Rev. A75, 042312 (2007) [journal][abstract]

High-fidelity entanglement of neutral cold atoms can be achieved by combining several already available techniques such as the creation or dissociation of neutral diatomic molecules, manipulating atoms with microfabricated structures (atom chips), and detecting single atoms with almost 100% efficiency. The fidelity of the resulting entanglement is robust against the details of dissociation process. Manipulating this entanglement with integrated or linear atom optics will open a perspective for quantum-information processing with neutral atoms.

@ARTICLE{)BoZhao,-High--2007, author = {) Bo Zhao and Zeng-Bing Chen and Jian-Wei Pan and Jörg Schmiedmayer and Alessio Recati and Grigory E. Astrakharchik and Tommaso Calarco}, title = {High-fidelity entanglement via molecular dissociation in integrated atom optics}, journal = {Phys. Rev. A}, volume = {75}, pages = {042312}, year = {2007} }

AUTORES/AS (p.o. de firma): ) Bo Zhao, Zeng-Bing Chen, Jian-Wei Pan, Jörg Schmiedmayer, Alessio Recati, Grigory E. Astrakharchik, and Tommaso Calarco TITULO: High-fidelity entanglement via molecular dissociation in integrated atom optics REF REVISTA/LIBRO: Phys. Rev. A 75, 042312 CLAVE: A FECHA PUBLICACION (*): 2007

[62] D. S. Petrov, G. E. Astrakharchik, C. Salomon, G. V. Shlyapnikov, Crystalline phase of strongly interacting Fermi mixtures, Phys. Rev. Lett.99, 130407 (2007) [journal][abstract]

We show that the system of weakly bound molecules of heavy and light fermionic atoms is characterized by a long-range intermolecular repulsion and can undergo a gas-crystal quantum transition if the mass ratio exceeds a critical value. For the critical mass ratio above 100 obtained in our calculations, this crystalline order can be observed as a superlattice in an optical lattice for heavy atoms with a small filling factor. We also find that this novel system is sufficiently stable with respect to molecular relaxation into deep bound states and to the process of trimer formation.

@ARTICLE{DSPet-Cryst-2007, author = {D. S. Petrov and G. E. Astrakharchik and C. Salomon and G. V. Shlyapnikov}, title = {Crystalline phase of strongly interacting Fermi mixtures}, journal = {Phys. Rev. Lett.}, volume = {99}, pages = {130407}, year = {2007} }

AUTORES/AS (p.o. de firma): D. S. Petrov, G. E. Astrakharchik, C. Salomon, G. V. Shlyapnikov TITULO: Crystalline phase of strongly interacting Fermi mixtures REF REVISTA/LIBRO: Phys. Rev. Lett. 99, 130407 CLAVE: A FECHA PUBLICACION (*): 2007

[63] G.E. Astrakharchik, J. Boronat, I.L. Kurbakov, and Yu.E. Lozovik, Quantum phase transition in a two-dimensional system of dipoles, Phys. Rev. Lett.98, 060405 (2007) [journal][abstract]

ground-state phase diagram two-dimensional Bose system with dipole-dipole interactions studied means quantum Monte Carlo technique Our calculation predicts quantum phase transition gas solid phase when density increases In gas phase condensate fraction calculated function density Using Feynman approximation collective excitation branch studied appearance roton minimum observed results static structure factor both sides gas-solid phase also presented Lindemann ratio transition point becomes γ=0 230(6) condensate fraction in gas phase estimated function density

@ARTICLE{GEAstra-Quant-2007, author = {G.E. Astrakharchik and J. Boronat and I.L. Kurbakov and Yu.E. Lozovik}, title = {Quantum phase transition in a two-dimensional system of dipoles}, journal = {Phys. Rev. Lett.}, volume = {98}, pages = {060405}, year = {2007} }

AUTORES/AS (p.o. de firma): G.E. Astrakharchik, J. Boronat, I.L. Kurbakov, and Yu.E. Lozovik TITULO: Quantum phase transition in a two-dimensional system of dipoles REF REVISTA/LIBRO: Phys. Rev. Lett. 98, 060405 CLAVE: A FECHA PUBLICACION (*): 2007

[64] G.E. Astrakharchik, J. Boronat, J. Casulleras, I.L. Kurbakov, and
Yu.E. Lozovik, Weakly interacting two-dimensional system of dipoles: limitations of the mean-field theory, Phys. Rev. A75, 063630 (2007) [journal][abstract]

consider homogeneous two-dimensional Bose gas with repulsive dipole-dipole interactions ground-state equation state calculated using diffusion Monte Carlo method s quantitative differences predictions commonly Gross-Pitaevskii mean-field ory static structure factor pair distribution function condensate fraction calculated in wide range gas parameter Differences mean-field ory reflected in frequency lowest “breathing” mode harmonically trapped systems

@ARTICLE{GEAstra-Weakl-2007, author = {G.E. Astrakharchik and J. Boronat and J. Casulleras and I.L. Kurbakov and
Yu.E. Lozovik}, title = {Weakly interacting two-dimensional system of dipoles: limitations of the mean-field theory}, journal = {Phys. Rev. A}, volume = {75}, pages = {063630}, year = {2007} }

AUTORES/AS (p.o. de firma): G.E. Astrakharchik, J. Boronat, J. Casulleras, I.L. Kurbakov, and
Yu.E. Lozovik TITULO: Weakly interacting two-dimensional system of dipoles: limitations of the mean-field theory REF REVISTA/LIBRO: Phys. Rev. A 75, 063630 CLAVE: A FECHA PUBLICACION (*): 2007

[65] Yu. E. Lozovik, I.L. Kurbakov, G.E. Astrakharchik, J. Boronat, and
Magnus Willander, Effects of strong correlations for 2D Bose-Einstein condensed dipolar excitons, Solid State Communications 144, 399 (2007) [journal][abstract]

By doing quantum Monte Carlo ab initio simulations dipolar excitons now under experimental actually strongly correlated systems Strong correlations manifest in significant deviations excitation spectra Bogoliubov large Bose condensate depletion short-range order in pair correlation function peak(s) in structure factor

@ARTICLE{YuELoz-Effec-2007, author = {Yu. E. Lozovik and I.L. Kurbakov and G.E. Astrakharchik and J. Boronat and
Magnus Willander}, title = {Effects of strong correlations for 2D Bose-Einstein condensed dipolar excitons}, journal = {Solid State Communications }, volume = {144}, pages = {399}, year = {2007} }

AUTORES/AS (p.o. de firma): Yu. E. Lozovik, I.L. Kurbakov, G.E. Astrakharchik, J. Boronat, and
Magnus Willander TITULO: Effects of strong correlations for 2D Bose-Einstein condensed dipolar excitons REF REVISTA/LIBRO: Solid State Communications 144, 399 CLAVE: A FECHA PUBLICACION (*): 2007

[66] G. E. Astrakharchik and S. Giorgini, Correlation functions of a Lieb-Liniger Bose gas, J. Phys. B: At. Mol. Opt. Phys.39, S1-S12 (2006) [journal][abstract]

The ground-state correlation functions of a one-dimensional homogeneous Bose system described by the Lieb–Liniger Hamiltonian are investigated by using exact quantum Monte Carlo techniques. This paper is an extension of a previous study published in Astrakharchik G E and Giorgini S (2003 Phys. Rev. A 68 031602). New results on the local three-body correlator as a function of the interaction strength are included and compared with the measured value from three-body loss experiments. We also carry out a thorough study of the short- and long-range behaviour of the one-body density matrix.

AUTORES/AS (p.o. de firma): G. E. Astrakharchik and S. Giorgini TITULO: Correlation functions of a Lieb-Liniger Bose gas REF REVISTA/LIBRO: J. Phys. B: At. Mol. Opt. Phys. 39, S1-S12 CLAVE: A FECHA PUBLICACION (*): 2006

[67] G. E. Astrakharchik, D. M. Gangardt, Yu.E Lozovik and I.A. Sorokin, Off-diagonal correlations of the Calogero-Sutherland model, Phys. Rev. E 7474, 021105 (2006) [journal][abstract]

We study correlation functions of the Calogero-Sutherland model in the whole range of the interaction parameter. Using the replica method we obtain analytical expressions for the long-distance asymptotics of the one-body density matrix in addition to the previously derived asymptotics of the pair-distribution function [D.M. Gangardt and A. Kamenev, Nucl. Phys. B 610, 578 (2001)]. The leading analytic and nonanalytic terms in the short-distance expansion of the one-body density matrix are discussed. Numerical results for these correlation functions are obtained using Monte Carlo techniques for all distances. The momentum distribution and static structure factor are calculated. The potential and kinetic energies are obtained using the Hellmann-Feynman theorem. Perfect agreement is found between the analytical expressions and numerical data. These results allow for the description of physical regimes of the Calogero-Sutherland model. The zero temperature phase diagram is found to be of a crossover type and includes quasicondensation, quasicrystallization and quasisupersolid regimes.

@ARTICLE{GEAstr-Off-d-2006, author = {G. E. Astrakharchik and D. M. Gangardt and Yu.E Lozovik and I.A. Sorokin}, title = {Off-diagonal correlations of the Calogero-Sutherland model}, journal = {Phys. Rev. E 74}, volume = {74}, pages = {021105}, year = {2006} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, D. M. Gangardt, Yu.E Lozovik and I.A. Sorokin TITULO: Off-diagonal correlations of the Calogero-Sutherland model REF REVISTA/LIBRO: Phys. Rev. E 74 74, 021105 CLAVE: A FECHA PUBLICACION (*): 2006

[68] S. Giorgini, G. E. Astrakharchik, J. Boronat, and J. Casulleras, Quantum Monte Carlo study of a Fermi gas in the BEC-BCS crossover, “Recent Progress in Many-Body Theories MB13”, ed. S. Hernández and H. Cataldo (World Scientific, Singapore) 228-237 (2006) [journal][abstract]

he ground-state properties of a two-component Fermi gas with attractive short-range interactions are calculated using the fixed-node diffusion Monte Carlo method. The interaction strength is varied over a wide range by tuning the value a of the s-wave scattering length of the two-body potential. We calculate the energy per particle, the one- and two-body density matrix as a function of the interaction strength. Results for the momentum distribution of the atoms, as obtained from the Fourier transform of the one-body density matrix, are reported as a function of the interaction strength. Off-diagonal long-range order in the system is investigated through the asymptotic behavior of the two-body density matrix. The condensate fraction of pairs is calculated in the unitary limit and on both sides of the BCS-BEC crossover.

@ARTICLE{SGiorgin-Quant-2006, author = {S. Giorgini and G. E. Astrakharchik and J. Boronat and J. Casulleras}, title = {Quantum Monte Carlo study of a Fermi gas in the BEC-BCS crossover}, journal = {“Recent Progress in Many-Body Theories MB13”, ed. S. Hernández and H. Cataldo (World Scientific, Singapore)}, pages = {228-237 }, year = {2006} }

AUTORES/AS (p.o. de firma): S. Giorgini, G. E. Astrakharchik, J. Boronat, and J. Casulleras TITULO: Quantum Monte Carlo study of a Fermi gas in the BEC-BCS crossover REF REVISTA/LIBRO: “Recent Progress in Many-Body Theories MB13”, ed. S. Hernández and H. Cataldo (World Scientific, Singapore) , 228-237 CLAVE: A FECHA PUBLICACION (*): 2006

[69] S. Giorgini, G. E. Astrakharchik, J. Boronat, and J. Casulleras, Quantum Monte Carlo study of a Fermi gas in the BEC-BCS crossover, Int. J. Mod. Phys. B20, 5189 (2006) [journal][abstract]

The ground-state properties of a two-component Fermi gas with attractive short-range interactions are calculated using the fixed-node diffusion Monte Carlo method. The interaction strength is varied over a wide range by tuning the value a of the s-wave scattering length of the two-body potential. We calculate the energy per particle, the one- and two-body density matrix as a function of the interaction strength. Results for the momentum distribution of the atoms, as obtained from the Fourier transform of the one-body density matrix, are reported as a function of the interaction strength. Off-diagonal long-range order in the system is investigated through the asymptotic behavior of the two-body density matrix. The condensate fraction of pairs is calculated in the unitary limit and on both sides of the BCS-BEC crossover.

@ARTICLE{SGiorgin-Quant-2006, author = {S. Giorgini and G. E. Astrakharchik and J. Boronat and J. Casulleras}, title = {Quantum Monte Carlo study of a Fermi gas in the BEC-BCS crossover}, journal = {Int. J. Mod. Phys. B}, volume = {20}, pages = {5189 }, year = {2006} }

AUTORES/AS (p.o. de firma): S. Giorgini, G. E. Astrakharchik, J. Boronat, and J. Casulleras TITULO: Quantum Monte Carlo study of a Fermi gas in the BEC-BCS crossover REF REVISTA/LIBRO: Int. J. Mod. Phys. B 20, 5189 CLAVE: A FECHA PUBLICACION (*): 2006

[70] A. S. Arkhipov, G. E. Astrakharchik, A. V. Belikov, and Yu. E. Lozovik , Ground-state properties of a one-dimensional system of dipoles, Pis’ma Zh. Eksp. Teor. Fiz.82, 41 (2005) [journal][abstract]

one-dimensional (1D) Bose system with dipole-dipole repulsion is studied at zero temperature by means of a quantum Monte Carlo method. It is shown that, in the limit of small linear density, the bosonic system of dipole moments acquires many properties of a system of noninteracting fermions. At larger linear densities, a variational Monte Carlo calculation suggests a crossover from a liquidlike to a solidlike state. The system is superfluid on the liquidlike side of the crossover and is normal deep on the solidlike side. Energy and structural functions are presented for a wide range of densities. Possible realizations of the model are 1D Bose atomic systems, with permanent dipoles or dipoles induced by static field or resonance radiation; or indirect excitons in coupled quantum wires; etc. We propose parameters of a possible experiment and discuss manifestations of the zero-temperature quantum crossover.

@ARTICLE{ASArkh-Groun-2005, author = {A. S. Arkhipov and G. E. Astrakharchik and A. V. Belikov and Yu. E. Lozovik }, title = {Ground-state properties of a one-dimensional system of dipoles}, journal = {Pis’ma Zh. Eksp. Teor. Fiz.}, volume = {82}, pages = {41}, year = {2005} }

AUTORES/AS (p.o. de firma): A. S. Arkhipov, G. E. Astrakharchik, A. V. Belikov, and Yu. E. Lozovik TITULO: Ground-state properties of a one-dimensional system of dipoles REF REVISTA/LIBRO: Pis’ma Zh. Eksp. Teor. Fiz. 82, 41 CLAVE: A FECHA PUBLICACION (*): 2005

[71] G. E. Astrakharchik, Local density approximation for a perturbative equation of state, Phys. Rev. A72, 063620 (2005) [journal][abstract]

Knowledge of a series expansion of the equation of state provides a deep insight into the physical nature of a quantum system. Starting from a generic “perturbative” equation of state of a homogeneous ultracold gas we make predictions for the properties of the gas in the presence of harmonic confinement. The local density approximation is used to obtain the chemical potential, total and release energies, Thomas-Fermi size, and density profile of a trapped system in three-, two-, and one-dimensional geometries. The frequencies of the lowest breathing modes are calculated using scaling and sum-rule approaches and could be used in an experiment as a high-precision tool for obtaining the expansion terms of the equation of state. The derived formalism is applied to dilute Bose and Fermi gases in different dimensions and to integrable one-dimensional models. The physical meaning of the expansion terms in a number of systems is discussed.

@ARTICLE{GEAstr-Local-2005, author = {G. E. Astrakharchik}, title = {Local density approximation for a perturbative equation of state}, journal = {Phys. Rev. A}, volume = {72}, pages = {063620 }, year = {2005} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik TITULO: Local density approximation for a perturbative equation of state REF REVISTA/LIBRO: Phys. Rev. A 72, 063620 CLAVE: A FECHA PUBLICACION (*): 2005

[72] G. E. Astrakharchik, J. Boronat, J. Casulleras, and S.
Giorgini, Beyond the Tonks-Girardeau gas: Strongly correlated regime in quasi-one-dimensional Bose gases, Phys. Rev. Lett.95, 190407 (2005) [journal][abstract]

e consider homogeneous 1D Bose gas with contact interactions large attractive coupling constant This system can realized in tight waveguides exploiting confinement induced resonance effective 1D scattering amplitude By using diffusion Monte Carlo method densities gaslike state well described gas hard rods critical density cluster formation estimated using variational Monte Carlo method behavior correlation functions frequency lowest breathing mode harmonically trapped systems s gas strongly correlated in Tonks-Girardeau regime

@ARTICLE{GEAstr-Beyon-2005, author = {G. E. Astrakharchik and J. Boronat and J. Casulleras and S.
Giorgini}, title = {Beyond the Tonks-Girardeau gas: Strongly correlated regime in quasi-one-dimensional Bose gases}, journal = {Phys. Rev. Lett.}, volume = {95}, pages = {190407}, year = {2005} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, J. Boronat, J. Casulleras, and S.
Giorgini TITULO: Beyond the Tonks-Girardeau gas: Strongly correlated regime in quasi-one-dimensional Bose gases REF REVISTA/LIBRO: Phys. Rev. Lett. 95, 190407 CLAVE: A FECHA PUBLICACION (*): 2005

[73] G. E. Astrakharchik, J. Boronat, J. Casulleras, and S. Giorgini, Momentum distribution and condensate fraction of a Fermi gas in the BCS-BEC crossover, Phys. Rev. Lett.95, 230405 (2005) [journal][abstract]

By using diffusion Monte Carlo method calculate one- two-body density matrix an interacting Fermi gas T=0 in BCS Bose-Einstein condensate (BEC) crossover Results momentum distribution atoms obtained Fourier transform one-body density matrix reported function interaction strength Off-diagonal long-range order in system investigated through asymptotic behavior two-body density matrix condensate fraction pairs calculated in unitary limit both sides BCS-BEC crossover

@ARTICLE{GEAstr-Momen-2005, author = {G. E. Astrakharchik and J. Boronat and J. Casulleras and S. Giorgini}, title = {Momentum distribution and condensate fraction of a Fermi gas in the BCS-BEC crossover}, journal = {Phys. Rev. Lett.}, volume = {95}, pages = {230405}, year = {2005} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, J. Boronat, J. Casulleras, and S. Giorgini TITULO: Momentum distribution and condensate fraction of a Fermi gas in the BCS-BEC crossover REF REVISTA/LIBRO: Phys. Rev. Lett. 95, 230405 CLAVE: A FECHA PUBLICACION (*): 2005

[74] G. E. Astrakharchik, R. Combescot, X. Leyronas and S. Stringari, Equation of state and collective frequencies of a trapped Fermi gas along the BEC-unitarity crossover, Phys. Rev. Lett.95, 030404 (2005) [journal][abstract]

We show that the study of the collective oscillations in a harmonic trap provides a very sensitive test of the equation of state of a Fermi gas near a Feshbach resonance. Using a scaling approach, whose high accuracy is proven by comparison with exact hydrodynamic solutions, the frequencies of the lowest compressional modes are calculated at T=0 in terms of a dimensionless parameter characterizing the equation of state. The predictions for the collective frequencies, obtained from the equations of state of mean-field BCS theory and of recent Monte Carlo calculations, are discussed in detail.

@ARTICLE{GEAstr-Equat-2005, author = {G. E. Astrakharchik and R. Combescot and X. Leyronas and S. Stringari}, title = {Equation of state and collective frequencies of a trapped Fermi gas along the BEC-unitarity crossover}, journal = {Phys. Rev. Lett.}, volume = {95}, pages = {030404}, year = {2005} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, R. Combescot, X. Leyronas and S. Stringari TITULO: Equation of state and collective frequencies of a trapped Fermi gas along the BEC-unitarity crossover REF REVISTA/LIBRO: Phys. Rev. Lett. 95, 030404 CLAVE: A FECHA PUBLICACION (*): 2005

[75] G. E. Astrakharchik, D. Blume, S. Giorgini, and B. E. Granger, Quasi-One-Dimensional Bose Gases with a Large Scattering Length, Phys. Rev. Lett.92, 030402 (2004) [journal][abstract]

Bose gases confined in highly elongated harmonic traps are investigated over a wide range of interaction strengths using quantum Monte Carlo techniques. We find that the properties of a Bose gas under tight transverse confinement are well reproduced by a 1D model Hamiltonian with contact interactions. We point out the existence of a unitary regime, where the properties of the quasi-1D Bose gas become independent of the actual value of the 3D scattering length a3D. In this unitary regime, the energy of the system is well described by a hard-rod equation of state. We investigate the stability of quasi-1D Bose gases with positive and negative a3D.

@ARTICLE{GEAstr-Quasi-2004, author = {G. E. Astrakharchik and D. Blume and S. Giorgini and B. E. Granger}, title = {Quasi-One-Dimensional Bose Gases with a Large Scattering Length}, journal = {Phys. Rev. Lett.}, volume = {92}, pages = {030402}, year = {2004} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, D. Blume, S. Giorgini, and B. E. Granger TITULO: Quasi-One-Dimensional Bose Gases with a Large Scattering Length REF REVISTA/LIBRO: Phys. Rev. Lett. 92, 030402 CLAVE: A FECHA PUBLICACION (*): 2004

[76] G. E. Astrakharchik, D. Blume, S. Giorgini, B. E. Granger, Quantum Monte Carlo study of quasi-one-dimensional Bose gases, J. Phys. B: At. Mol. Opt. Phys. 37, 5205 (2004) [journal][abstract]

We study the behaviour of quasi-one-dimensional (quasi-1D) Bose gases by Monte Carlo techniques, i.e. by the variational Monte Carlo, the diffusion Monte Carlo and the fixed-node diffusion Monte Carlo techniques. Our calculations confirm and extend our results of an earlier study (Astrakharchik et al 2003 Preprint cond-mat/0308585). We find that a quasi-1D Bose gas (i) is well described by a 1D model Hamiltonian with contact interactions and renormalized coupling constant; (ii) reaches the Tonks–Girardeau regime for a critical value of the 3D scattering length a3D; (iii) enters a unitary regime for |a3D| → ∞, where the properties of the gas are independent of a3D and are similar to those of a 1D gas of hard-rods and (iv) becomes unstable against cluster formation for a critical value of the 1D gas parameter. The accuracy and implications of our results are discussed in detail.

@ARTICLE{GEAstr-Quant-2004, author = {G. E. Astrakharchik and D. Blume and S. Giorgini and B. E. Granger}, title = {Quantum Monte Carlo study of quasi-one-dimensional Bose gases}, journal = {J. Phys. B: At. Mol. Opt. Phys. }, volume = {37}, pages = {5205}, year = {2004} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, D. Blume, S. Giorgini, B. E. Granger TITULO: Quantum Monte Carlo study of quasi-one-dimensional Bose gases REF REVISTA/LIBRO: J. Phys. B: At. Mol. Opt. Phys. 37, 5205 CLAVE: A FECHA PUBLICACION (*): 2004

[77] G. E. Astrakharchik, D. Blume, S. Giorgini, L. P. Pitaevskii, Interacting fermions in highly elongated harmonic traps, Phys. Rev. Lett.93, 050402 (2004) [journal][abstract]

Quasi-one-dimensional two-component Fermi gases with effectively attractive and repulsive interactions are characterized for arbitrary interaction strength. The ground-state properties of the gas confined in highly elongated harmonic traps are determined within the local density approximation. For strong attractive effective interactions the existence of a molecular Tonks-Girardeau gas is predicted. The frequency of the lowest breathing mode is calculated as a function of the coupling strength for both attractive and repulsive interactions.

@ARTICLE{GEAstr-Inter-2004, author = {G. E. Astrakharchik and D. Blume and S. Giorgini and L. P. Pitaevskii}, title = {Interacting fermions in highly elongated harmonic traps}, journal = {Phys. Rev. Lett.}, volume = {93}, pages = {050402}, year = {2004} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, D. Blume, S. Giorgini, L. P. Pitaevskii TITULO: Interacting fermions in highly elongated harmonic traps REF REVISTA/LIBRO: Phys. Rev. Lett. 93, 050402 CLAVE: A FECHA PUBLICACION (*): 2004

[78] G. E. Astrakharchik, J. Boronat, J. Casulleras, and S. Giorgini, Equation of State of a Fermi Gas in the BEC-BCS Crossover: A Quantum Monte Carlo Study, Phys. Rev. Lett.93, 200404 (2004) [journal][abstract]

We calculate the equation of state of a two-component Fermi gas with attractive short-range interspecies interactions using the fixed-node diffusion Monte Carlo method. The interaction strength is varied over a wide range by tuning the value a of the s-wave scattering length of the two-body potential. For a>0 and a smaller than the inverse Fermi wave vector our results show a molecular regime with repulsive interactions well described by the dimer-dimer scattering length am=0.6a. The pair correlation functions of parallel and opposite spins are also discussed as a function of the interaction strength.

@ARTICLE{GEAstr-Equat-2004, author = {G. E. Astrakharchik and J. Boronat and J. Casulleras and S. Giorgini}, title = {Equation of State of a Fermi Gas in the BEC-BCS Crossover: A Quantum Monte Carlo Study}, journal = {Phys. Rev. Lett.}, volume = {93}, pages = {200404}, year = {2004} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, J. Boronat, J. Casulleras, and S. Giorgini TITULO: Equation of State of a Fermi Gas in the BEC-BCS Crossover: A Quantum Monte Carlo Study REF REVISTA/LIBRO: Phys. Rev. Lett. 93, 200404 CLAVE: A FECHA PUBLICACION (*): 2004

[79] G.E. Astrakharchik and L.P. Pitaevskii, Motion of a heavy impurity through a Bose-Einstein condensate, Phys. Rev. A70, 013608 (2004) [journal][abstract]

We study the motion of a pointlike impurity in a Bose-Einstein condensate at T=0. By solving the Gross-Pitaevskii (GP) equation in a perturbative manner we calculate the induced mass of the impurity and the drag force on the impurity in three-, two-, and one-dimensional (1D) cases. The relationship between the induced mass and the normal mass of fluid is found, and coincides with the result of the Bogoliubov theory. The drag force appears for the supersonic motion of the impurity. In 1D the drag force is investigated also on the basis of the exact Lieb-Liniger theory, using the dynamic form factor, which has been evaluated by the Haldane method of the calculation of correlation functions. In this theory the force appears for an arbitrarily small velocity of the impurity. The possibility of measuring the form factor in existing experiments is noted.

@ARTICLE{GEAstra-Motio-2004, author = {G.E. Astrakharchik and L.P. Pitaevskii}, title = {Motion of a heavy impurity through a Bose-Einstein condensate}, journal = {Phys. Rev. A}, volume = {70}, pages = {013608}, year = {2004} }

AUTORES/AS (p.o. de firma): G.E. Astrakharchik and L.P. Pitaevskii TITULO: Motion of a heavy impurity through a Bose-Einstein condensate REF REVISTA/LIBRO: Phys. Rev. A 70, 013608 CLAVE: A FECHA PUBLICACION (*): 2004

[80] G. E. Astrakharchik and S. Giorgini, Correlation functions and momentum distribution of one-dimensional Bose systems, Phys. Rev. A 68, 031602(R) (2003) [journal][abstract]

The ground-state correlation properties of a one-dimensional Bose system described by the Lieb-Liniger Hamiltonian are investigated by using exact quantum Monte Carlo techniques. The pair distribution function, static structure factor, one-body density matrix, and momentum distribution of a homogeneous system are calculated for different values of the gas parameter ranging from the Tonks-Girardeau to the mean-field regime. Results for the momentum distribution of a harmonically trapped gas in configurations relevant to experiments are also presented.

@ARTICLE{GEAstr-Corre-2003, author = {G. E. Astrakharchik and S. Giorgini}, title = {Correlation functions and momentum distribution of one-dimensional Bose systems}, journal = {Phys. Rev. A }, volume = {68}, pages = {031602(R)}, year = {2003} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik and S. Giorgini TITULO: Correlation functions and momentum distribution of one-dimensional Bose systems REF REVISTA/LIBRO: Phys. Rev. A 68, 031602(R) CLAVE: A FECHA PUBLICACION (*): 2003

[81] G. E. Astrakharchik and S. Giorgini, Quantum Monte Carlo study of the three- to one-dimensional crossover for a trapped Bose gas, Phys. Rev. A 66, 053614 (2002) [journal][abstract]

We investigate the crossover from three to one dimension in a Bose gas confined in highly anisotropic traps. By using quantum Monte Carlo techniques, we solve the many-body Schrödinger equation for the ground state and obtain exact results for the energy per particle and the mean square radii of the cloud in the transverse and longitudinal direction. Results are compared with the predictions of mean-field theory obtained from the Gross-Pitaevskii equation and with the one-dimensional Lieb-Liniger equation of state. We explicitly prove the occurrence of important beyond mean-field effects, including the appearance of Fermi-like properties as the system enters the Tonks gas regime.

@ARTICLE{GEAstr-Quant-2002, author = {G. E. Astrakharchik and S. Giorgini}, title = {Quantum Monte Carlo study of the three- to one-dimensional crossover for a trapped Bose gas}, journal = {Phys. Rev. A }, volume = {66}, pages = {053614}, year = {2002} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik and S. Giorgini TITULO: Quantum Monte Carlo study of the three- to one-dimensional crossover for a trapped Bose gas REF REVISTA/LIBRO: Phys. Rev. A 66, 053614 CLAVE: A FECHA PUBLICACION (*): 2002

[82] G. E. Astrakharchik, J.Boronat, J. Casulleras and S. Giorgini, Superfluidity and Bose-Einstein condensation in a Bose gas with disorder, Phys. Rev. A66, 023603 (2002) [journal] [arXiv][abstract]

We investigate the phenomenon of Bose-Einstein condensation and superfluidity in a Bose gas at zero temperature with disorder. By using the diffusion Monte Carlo method, we calculate the superfluid and the condensate fraction of the system as a function of density and strength of disorder. In the regime of weak disorder we find agreement with the analytical results obtained within the Bogoliubov model. For strong disorder the system enters an unusual regime where the superfluid fraction is smaller than the condensate fraction.

@ARTICLE{GEAstr-Super-2002, author = {G. E. Astrakharchik and J.Boronat and J. Casulleras and S. Giorgini}, title = {Superfluidity and Bose-Einstein condensation in a Bose gas with disorder}, journal = {Phys. Rev. A}, volume = {66}, pages = {023603}, year = {2002} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, J.Boronat, J. Casulleras and S. Giorgini TITULO: Superfluidity and Bose-Einstein condensation in a Bose gas with disorder REF REVISTA/LIBRO: Phys. Rev. A 66, 023603 CLAVE: A FECHA PUBLICACION (*): 2002

[83] G. E. Astrakharchik, A. I. Belousov, Yu. E. Lozovik, Properties of two-dimensional dusty plasma clusters, Phys. Lett. A258, 123-130 (1999) [journal][abstract]

A two-dimensional classical cluster of particles interacting through a screened Coulomb potential is studied. This system can be used as a model for `dusty particles' in high-frequency discharge plasma. For systems consisting of N=2–40 particles and confined by a harmonic potential we find ground-state configurations, eigenfrequencies and eigenvectors for the normal modes as a function of the Debye screening length RD in plasma. Variations in RD cause changes in the ground-state structure of clusters, each structural rearrangement can be considered as a phase transition of first or second order (with respect to parameter RD). Monte Carlo and molecular dynamics are used to study in detail the melting of the clusters as the temperature is increased. By varying the density and the temperature of plasma, to which the particles are immersed, one can modulate thermodynamical properties of the system, transforming it in a controllable way to an ordered (crystal-like), orientationaly disordered or totally disordered (liquid-like) states. The possibility of dynamical coexistence phenomena in small clusters is discussed.

@ARTICLE{GEAstr-Prope-1999, author = {G. E. Astrakharchik and A. I. Belousov and Yu. E. Lozovik}, title = {Properties of two-dimensional dusty plasma clusters}, journal = {Phys. Lett. A}, volume = {258}, pages = {123-130 }, year = {1999} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, A. I. Belousov, Yu. E. Lozovik TITULO: Properties of two-dimensional dusty plasma clusters REF REVISTA/LIBRO: Phys. Lett. A 258, 123-130 CLAVE: A FECHA PUBLICACION (*): 1999

[84] G. E. Astrakharchik, A. I. Belousov, Yu. E. Lozovik, Two-dimensional mesoscopic dusty plasma clusters: Structure and phase transitions, JETP89, 696 (1999) [journal][abstract]

A two-dimensional mesoscopic cluster of “dusty plasma” particles, which can be interpreted as a system of microparticles in an rf gas discharge, is investigated. The ground-state configurations and corresponding eigenfrequencies and eigenvectors are found for clusters of N=22–40 particles in a harmonic confining potential. It is shown that a change in the Debye screening length R of the particle charge in the plasma can cause structural transformations of the ground state of the system, manifested as first-order or second-order phase transitions with respect to the parameter R. The disorder (“melting”) of the clusters is analyzed in detail by Monte Carlo simulation and molecular dynamics. By varying the characteristic range of particle interaction in a cluster, it is possible to modulate its thermodynamic properties and the character of the phase transitions, thereby causing a controlled transition of the system into the fully ordered, orientationally disordered, or fully disordered state. The possibility of dusty plasma clusters coexisting in different states is discussed.

@ARTICLE{GEAstr-Two-d-1999, author = {G. E. Astrakharchik and A. I. Belousov and Yu. E. Lozovik}, title = {Two-dimensional mesoscopic dusty plasma clusters: Structure and phase transitions}, journal = {JETP}, volume = {89}, pages = {696}, year = {1999} }

AUTORES/AS (p.o. de firma): G. E. Astrakharchik, A. I. Belousov, Yu. E. Lozovik TITULO: Two-dimensional mesoscopic dusty plasma clusters: Structure and phase transitions REF REVISTA/LIBRO: JETP 89, 696 CLAVE: A FECHA PUBLICACION (*): 1999