Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:0710.5187 · Physical Review A

Phase coherence and superfluid-insulator transition in a disordered Bose-Einstein condensate

Yong P. Chen, J. M. Hitchcock, D. Dries, Mark D. Junker, C. Welford, Randall G. Hulet

Published Mar 31, 2008• 125 citations
arXivHTMLPDF

Abstract

We have studied the effects of a disordered optical potential on the transport and phase coherence of a Bose-Einstein condensate (BEC) of $^{7}\text{L}\text{i}$ atoms. At moderate disorder strengths $({V}_{D})$, we observe inhibited transport and damping of dipole excitations, while in time-of-flight images, random but reproducible interference patterns are observed. In situ images reveal that the appearance of interference is correlated with density modulation, without complete fragmentation. At higher ${V}_{D}$, the interference contrast diminishes as the BEC fragments into multiple pieces with little phase coherence.

DOI
10.1103/physreva.77.033632

Related papers

Transport and phase coherence studies of a quantum gas in a disordered potential

Hitchock, James Michael

The Study of transport and phase coherence in a Bose-Einstein condensate (BEC) of 7 Li subjected to a 1D disordered potential, provides an excellent system to explore the effects of impurities on a quantum gas. Observations of the median cloud position as the BEC is moved through the disorder potential provide evidence of inhibited transport due to classical reflections. Careful study of the damping coefficient for dipole oscillations shows a power law relationship with disorder strength ( V D ). A highly elongated BEC and large disorder length scale, (σ d = 14 pm), allow direct probing of disorder induced density modulations in the in-situ BEC. Large density fluctuations are observed to evolve from the in-situ density modulations for moderate V D , and phase coherence is suppressed at large V D . An improved speckle pattern has been designed, for future experiments, with a reduced σ d and an aspect ratio that more closely matches the BEC.

•Jan 1, 2008•0 citations

Transport properties of a Bose-Einstein condensate with tunable interactions in the presence of a disordered or single defect potential

D. Dries

Bose-Einstein condensates (BECs) have proven to be remarkable systems with which to study some of the foundational models of condensed matter physics. The observation of a critical velocity for the breakdown of superfluidity in a BEC and the superfluid to Mott insulator transition observed in a BEC trapped by an optical lattice are but two examples of the, by now, dozens of exciting results in this field, which combines theoretical tools from condensed matter physics with state-of-the-art experimental techniques from ultra-cold atomic physics. However, any real condensed matter system has to contend with the effects of disorder, a phenomena notably absent in the inherently clean BEC systems. We have developed and implemented a way to add well characterized disorder in a controlled way to the otherwise clean BEC system using the light field from a laser speckle pattern. Using this system, we have investigated the effects of disorder or a single Gaussian defect, on the collective dipole motion of a BEC of 7Li in an optical trap. In addition, we perform transport experiments on a weakly interacting BEC expanding in a disordered one-dimensional atom wave-guide. We have observed that in such a system, the wave nature of matter can lead to spectacular and counterintuitive phenomena. Specifically, we verify that this system exhibits Anderson localization, a phenomena fundamentally resulting from the interference of multiply scattered matter waves. In such a state, the localized gas behaves as an insulator in a regime where it is classically expected to be conducting.\nWe also present results of experiments regarding a repulsive BEC scattering from a semi-permeable, single defect potential. We investigate the transport properties of such a system with special emphasis on the velocity and defect strength dependent dissipation of the collective dipole motion of the BEC. Finally, we present the results of our experiments on the scattering properties of bright matter wave solitons. We have observed fragmentation of the soliton in a disordered potential as well as both splitting and recombination of a soliton after interacting with a single repulsive defect potential.

•Jan 1, 2010•0 citations

Dissipative transport of a Bose-Einstein condensate

D. Dries, S. E. Pollack, J. M. Hitchcock +1 more

We investigate the effects of impurities, either correlated disorder or a single Gaussian defect, on the collective dipole motion of a Bose-Einstein condensate of $^{7}\mathrm{Li}$ in an optical trap. We find that this motion is damped at a rate dependent on the impurity strength, condensate center-of-mass velocity, and interatomic interactions. Damping in the Thomas-Fermi regime depends universally on the disordered potential strength scaled to the condensate chemical potential and the condensate velocity scaled to the speed of sound. The damping rate is comparatively small in the weakly interacting regime, and, in this case, is accompanied by strong condensate fragmentation. In situ and time-of-flight images of the atomic cloud provide evidence that this fragmentation is driven by dark soliton formation.

arXiv:1004.1891•Physical Review A•Sep 8, 2010•87 citations

Disorder Induced Dynamic Equilibrium Localization and Random Phase Steps of Bose—Einstein Condensates

Yafan Duan, Zhen Xu, Jun Qian +3 more

We numerically analyze the dynamic behavior of Bose—Einstein condensate (BEC) in a one-dimensional disordered potential before it completely loses spatial quantum coherence. We find that both the disorder statistics and the atom interactions produce remarkable effects on localization. We also find that the single phase of the initial condensate is broken into many small pieces while the system approaches localization, showing a counter-intuitive step-wise phase but not a thoroughly randomized phase. Although the condensates as a whole show less flow and expansion, the currents between adjacent phase steps retain strong time dependence. Thus we show explicitly that the localization of a finite size Bose—Einstein condensate is a dynamic equilibrium state.

Chinese Physics Letters•Oct 1, 2011•1 citation

Density Modulations in an Elongated BEC Released from a Disordered Potential

David Clément, Philippe Bouyer, Alain Aspect +1 more

We observe large density modulations in time-of-flight images of elongated Bose-Einstein condensates, initially confined in a harmonic trap and in the presence of weak disorder. The development of these modulations during the time-of-flight and their dependence with the disorder are investigated. We render an account of this effect using numerical and analytical calculations. Our analysis shows how the observed large modulations originate from the weak initial density modulations induced by the disorder, and do not require phase fluctuations (thermal or quantum) in the initial condensate.

•Oct 10, 2007•0 citations

Density Modulations in an Elongated BEC Released from a Disordered Potential: What Can We Learn ?

David Clément, Philippe Bouyer, Alain Aspect +1 more

We observe large density modulations in time-of-flight images of elongated Bose-Einstein condensates, initially confined in a harmonic trap and in the presence of weak disorder. The development of these modulations during the time-of-flight and their dependence with the disorder are investigated. We render an account of this effect using numerical and analytical calculations. We conclude that the observed large density modulations originate from the weak initial density modulations induced by the disorder, and not from initial phase fluctuations (thermal or quantum).

•Jan 24, 2008•0 citations
We have studied the effects of a disordered optical potential on the transport and phase coherence of a Bose-Einstein condensate (BEC) of 7Li^{7}\text{L}\text{i}7Li atoms. At moderate disorder strengths (VD)({V}_{D})(VD​), we observe inhibited transport and damping of dipole excitations, while in time-of-flight images, random but reproducible interference patterns are observed. In situ images reveal that the appearance of interference is correlated with density modulation, without complete fragmentation. At higher VD{V}_{D}VD​, the interference contrast diminishes as the BEC fragments into multiple pieces with little phase coherence.
The Study of transport and phase coherence in a Bose-Einstein condensate (BEC) of 7 Li subjected to a 1D disordered potential, provides an excellent system to explore the effects of impurities on a quantum gas. Observations of the median cloud position as the BEC is moved through the disorder potential provide evidence of inhibited transport due to classical reflections. Careful study of the damping coefficient for dipole oscillations shows a power law relationship with disorder strength ( V D ). A highly elongated BEC and large disorder length scale, (σ d = 14 pm), allow direct probing of disorder induced density modulations in the in-situ BEC. Large density fluctuations are observed to evolve from the in-situ density modulations for moderate V D , and phase coherence is suppressed at large V D . An improved speckle pattern has been designed, for future experiments, with a reduced σ d and an aspect ratio that more closely matches the BEC.
Bose-Einstein condensates (BECs) have proven to be remarkable systems with which to study some of the foundational models of condensed matter physics. The observation of a critical velocity for the breakdown of superfluidity in a BEC and the superfluid to Mott insulator transition observed in a BEC trapped by an optical lattice are but two examples of the, by now, dozens of exciting results in this field, which combines theoretical tools from condensed matter physics with state-of-the-art experimental techniques from ultra-cold atomic physics. However, any real condensed matter system has to contend with the effects of disorder, a phenomena notably absent in the inherently clean BEC systems. We have developed and implemented a way to add well characterized disorder in a controlled way to the otherwise clean BEC system using the light field from a laser speckle pattern. Using this system, we have investigated the effects of disorder or a single Gaussian defect, on the collective dipole motion of a BEC of 7Li in an optical trap. In addition, we perform transport experiments on a weakly interacting BEC expanding in a disordered one-dimensional atom wave-guide. We have observed that in such a system, the wave nature of matter can lead to spectacular and counterintuitive phenomena. Specifically, we verify that this system exhibits Anderson localization, a phenomena fundamentally resulting from the interference of multiply scattered matter waves. In such a state, the localized gas behaves as an insulator in a regime where it is classically expected to be conducting.\nWe also present results of experiments regarding a repulsive BEC scattering from a semi-permeable, single defect potential. We investigate the transport properties of such a system with special emphasis on the velocity and defect strength dependent dissipation of the collective dipole motion of the BEC. Finally, we present the results of our experiments on the scattering properties of bright matter wave solitons. We have observed fragmentation of the soliton in a disordered potential as well as both splitting and recombination of a soliton after interacting with a single repulsive defect potential.
We investigate the effects of impurities, either correlated disorder or a single Gaussian defect, on the collective dipole motion of a Bose-Einstein condensate of 7Li^{7}\mathrm{Li}7Li in an optical trap. We find that this motion is damped at a rate dependent on the impurity strength, condensate center-of-mass velocity, and interatomic interactions. Damping in the Thomas-Fermi regime depends universally on the disordered potential strength scaled to the condensate chemical potential and the condensate velocity scaled to the speed of sound. The damping rate is comparatively small in the weakly interacting regime, and, in this case, is accompanied by strong condensate fragmentation. In situ and time-of-flight images of the atomic cloud provide evidence that this fragmentation is driven by dark soliton formation.
We numerically analyze the dynamic behavior of Bose—Einstein condensate (BEC) in a one-dimensional disordered potential before it completely loses spatial quantum coherence. We find that both the disorder statistics and the atom interactions produce remarkable effects on localization. We also find that the single phase of the initial condensate is broken into many small pieces while the system approaches localization, showing a counter-intuitive step-wise phase but not a thoroughly randomized phase. Although the condensates as a whole show less flow and expansion, the currents between adjacent phase steps retain strong time dependence. Thus we show explicitly that the localization of a finite size Bose—Einstein condensate is a dynamic equilibrium state.
We observe large density modulations in time-of-flight images of elongated Bose-Einstein condensates, initially confined in a harmonic trap and in the presence of weak disorder. The development of these modulations during the time-of-flight and their dependence with the disorder are investigated. We render an account of this effect using numerical and analytical calculations. Our analysis shows how the observed large modulations originate from the weak initial density modulations induced by the disorder, and do not require phase fluctuations (thermal or quantum) in the initial condensate.
We observe large density modulations in time-of-flight images of elongated Bose-Einstein condensates, initially confined in a harmonic trap and in the presence of weak disorder. The development of these modulations during the time-of-flight and their dependence with the disorder are investigated. We render an account of this effect using numerical and analytical calculations. We conclude that the observed large density modulations originate from the weak initial density modulations induced by the disorder, and not from initial phase fluctuations (thermal or quantum).