Effects of disorder on quantum fluctuations and superfluid density of a Bose-Einstein condensate in a two-dimensional optical lattice

Hu, Ying; Liang, Zhaoxin; Hu, Bambi

doi:10.1103/physreva.80.043629

Cited by 15 publications

(37 citation statements)

References 48 publications

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“…As a consequence, the population of momenta k = 0 does not measure the depletion of inhomogeneous condensates, contrary to what has been suggested, unfortunately, in the groundbreaking work of Huang and Meng [13], followed in this respect by numerous others [14][15][16][17][18][19][20][21]. Within the Huang-Meng approximation scheme, one cannot calculate the condensate depletion induced by the external potential; this is achieved, to our knowledge for the first time, in this paper (section 4).…”

Section: Condensate Deformation Does Not Reduce the Mean-field Condenmentioning

confidence: 59%

“…The perturbation expansion (8) and (9) of the condensate amplitude k in powers of V implies a similar expansion for the Bogoliubov transformation matrices (19) and (20):…”

Section: Weak-potential Expansionmentioning

confidence: 85%

“…In the following, we pursue a fully analytical calculation by a perturbative expansion up to order V 2 in the bare external potential. In section 3.4 the Bogoliubov transformation matrices (19) and (20) are determined together with the scattering matrix elements (24) and (25). In section 3.5, the results are collected into a compact expression for the momentum distribution.…”

Section: Bogolon Populationsmentioning

confidence: 99%

“…The matrices u k p and v k p as defined by (19) and (20) are the Fourier components with wave vector k of the modes u p (r) and v p (r) defined in [8]. As explained there, the momentum index p can be used to label the modes even in the inhomogeneous setting.…”

Section: Appendix Transformation To Bogoliubov Quasi-particlesmentioning

confidence: 99%

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Condensate deformation and quantum depletion of Bose–Einstein condensates in external potentials

2012

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The one-body density matrix of weakly interacting condensed bosons in external potentials is calculated using inhomogeneous Bogoliubov theory. We determine the condensate deformation caused by weak external potentials at the mean-field level. The momentum distribution of quantum fluctuations around the deformed ground state is obtained analytically and finally, the resulting quantum depletion is calculated. The depletion due to the external potential, or potential depletion for short, is a small correction to the homogeneous depletion, validating our inhomogeneous Bogoliubov theory. Analytical results are derived for weak lattices and spatially correlated random potentials, with simple, universal results in the Thomas-Fermi limit of very smooth potentials. References 19has (at least) one macroscopically occupied eigenmode. As stated very clearly by Penrose and Onsager in their original paper, only if the system is completely homogeneous (i.e. translation-invariant under periodic boundary conditions), condensation occurs into a single momentum component, namely the state with wave vector k = 0 in the condensate rest frame.

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Section: Condensate Deformation Does Not Reduce the Mean-field Condenmentioning

confidence: 59%

“…The perturbation expansion (8) and (9) of the condensate amplitude k in powers of V implies a similar expansion for the Bogoliubov transformation matrices (19) and (20):…”

Section: Weak-potential Expansionmentioning

confidence: 85%

Section: Bogolon Populationsmentioning

confidence: 99%

Section: Appendix Transformation To Bogoliubov Quasi-particlesmentioning

confidence: 99%

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Condensate deformation and quantum depletion of Bose–Einstein condensates in external potentials

2012

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“…For instance, in recent proposals concerning the preparations of many-body states and nonequilibrium quantum phases based on engineering a superfluid reservoir [33][34][35][36], the sound velocity acts as a key parameter in determining the system-bath coupling. The control of sound velocity of a superfluid, such as by using various carefully configured external traps [16][17][18][19][20][21][22][23][24][25][26][27][28][29] , therefore constitutes an important ingredient of the reservoir engineering.…”

Section: Introductionmentioning

confidence: 99%

Unusual behavior of sound velocity of a Bose gas in an optical superlattice at quasi-one-dimension

Chen

et al. 2014

Eur. Phys. J. D

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A Bose gas trapped in a one-dimensional optical superlattice has emerged as a novel superfluid characterized by tunable lattice topologies and tailored band structures. In this work, we focus on the propagation of sound in such a novel system and have found new features on sound velocity, which arises from the interplay between the two lattices with different periodicity and is not present in the case of a condensate in a monochromatic optical lattice. Particularly, this is the first time that the sound velocity is found to first increase and then decrease as the superlattice strength increases even at one dimension. Such unusual behavior can be analytically understood in terms of the competition between the decreasing compressibility and the increasing effective mass due to the increasing superlattice strength. This result suggests a new route to engineer the sound velocity by manipulating the superlattice's parameters. All the calculations based on the mean-field theory are justified by checking the exponent γ of the off-diagonal one-body density matrix that is much smaller than 1. Finally, the conditions for possible experimental realization of our scenario are also discussed.

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Non-equilibrium disordered Bose gases: condensation, superfluidity and dynamical Bose glass

Chen

Liang

et al. 2015

J. Phys. B: At. Mol. Opt. Phys.

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In an equilibrium three-dimensional (3D) disordered condensate, it is well established that disorder can generate an amount of normal fluid ρ n equaling to 4 3 of ρ ex , where ρ ex is a sum of interaction-induced quantum depletion and disorder-induced condensate deformation. The concept that the superfluid is more volatile to the existence of disorder than the condensate is crucial to the understanding of the Bose glass phase. In this work, we show that, by bringing a weakly disordered 3D condensate to non-equilibrium regime via a quantum quench in the interaction, disorder can destroy superfluid significantly more, leading to a steady state of Hamiltonian H f in which the ρ n far exceeds 4 3 of the ρ ex. This suggests the possibility of engineering Bose glass in the dynamic regime. Here, we refer to the dynamical Bose glass as the case where in the steady state of quenched condensate, the superfluid density goes to zero while the condensate density remains finite. As both the ρ n and ρ ex are measurable quantities, our results allow an experimental demonstration of the dramatized interplay between the disorder and interaction in the non-equilibrium scenario.

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Effects of disorder on quantum fluctuations and superfluid density of a Bose-Einstein condensate in a two-dimensional optical lattice

Cited by 15 publications

References 48 publications

Condensate deformation and quantum depletion of Bose–Einstein condensates in external potentials

Condensate deformation and quantum depletion of Bose–Einstein condensates in external potentials

Unusual behavior of sound velocity of a Bose gas in an optical superlattice at quasi-one-dimension

Non-equilibrium disordered Bose gases: condensation, superfluidity and dynamical Bose glass

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