Reservoir interactions during Bose-Einstein condensation: Modified critical scaling in the Kibble-Zurek mechanism of defect formation

McDonald, R. G.; Bradley, Ashton S.

doi:10.1103/physreva.92.033616

“…We believe our predictions suggest an interesting regime for experimental testing. The need for rigorous testing [76] of dissipative quantum field theories describing open systems is further motivated by interest in superfluid internal convection [77,78], farfrom equilibrium dynamics [25,79], thermalisation [80,81], and critical phenomena [48,[82][83][84][85].…”

Section: Discussionmentioning

confidence: 99%

Reservoir interactions of a vortex in a trapped three-dimensional Bose-Einstein condensate

Rooney

¹

,

Allen

²

,

Zülicke

³

et al. 2016

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We simulate the dissipative evolution of a vortex in a trapped finite-temperature dilute-gas Bose-Einstein condensate using first-principles open-systems theory. Simulations of the complete stochastic projected GrossPitaevskii equation for a partially condensed Bose gas containing a single quantum vortex show that the transfer of condensate energy to the incoherent thermal component without population transfer provides an important channel for vortex decay. For the lower temperatures considered, this effect is significantly larger that the population transfer process underpinning the standard theory of vortex decay, and is the dominant determinant of the vortex lifetime. A comparison with the Zaremba-Nikuni-Griffin kinetic (two-fluid) theory further elucidates the role of the particle transfer interaction, and suggests the need for experimental testing of reservoir interaction theory. The dominance of this particular energetic decay mechanism for this open quantum system should be testable with current experimental setups, and its observation would have broad implications for the dynamics of atomic matter waves and experimental studies of dissipative phenomena.

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“…[60][61][62] and Refs. [41,[63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78], respectfully. Notably, the SPGPE has been able to quantitatively describe experimental results, such as in Refs.…”

Section: Classical Field Methodologymentioning

confidence: 96%

Superflow decay in a toroidal Bose gas: The effect of quantum and thermal fluctuations

Mehdi

¹

,

Bradley

²

,

Hope

³

et al. 2021

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We theoretically investigate the stochastic decay of persistent currents in a toroidal ultracold atomic superfluid caused by a perturbing barrier. Specifically, we perform detailed three-dimensional simulations to model the experiment of Kumar et al. in [Phys. Rev. A 95 021602 (2017)], which observed a strong temperature dependence in the timescale of superflow decay in an ultracold Bose gas. Our ab initio numerical approach exploits a classical-field framework that includes thermal fluctuations due to interactions between the superfluid and a thermal cloud, as well as the intrinsic quantum fluctuations of the Bose gas. In the low-temperature regime our simulations provide a quantitative description of the experimental decay timescales, improving on previous numerical and analytical approaches. At higher temperatures, our simulations give decay timescales that range over the same orders of magnitude observed in the experiment, however, there are some quantitative discrepancies that are not captured by any of the mechanisms we explore. Our results suggest a need for further experimental and theoretical studies into superflow stability.

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“…[59][60][61] and Refs. [41,[62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77], respectfully. Notably, the SPGPE has been able to quantitatively, describe experimental results, such as in Refs.…”

Section: Classical Field Methodologymentioning

confidence: 96%

Superflow decay in a toroidal Bose gas: The effect of quantum and thermal fluctuations

Mehdi,

Bradley,

Hope

et al. 2021

Preprint

0

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We theoretically investigate the stochastic decay of persistent currents in a toroidal ultracold atomic superfluid caused by a perturbing barrier. Specifically, we perform detailed threedimensional simulations to model the experiment of Kumar et al. in [Phys. Rev. A 95 021602 (2017)], which observed a strong temperature dependence in the timescale of superflow decay in an ultracold Bose gas. Our ab initio numerical approach exploits a classical-field framework that includes thermal fluctuations due to interactions between the superfluid and a thermal cloud, as well as the intrinsic quantum fluctuations of the Bose gas. In the low-temperature regime our simulations provide a quantitative description of the experimental decay timescales. At higher temperatures, our simulations give decay timescales that range over the same orders of magnitude observed in the experiment, however there are some quantitative discrepancies. In particular, we find a much larger perturbing barrier strength is required to simulate a particular decay timescale (between ∼0.15µ and ∼0.5µ), as compared to the experiment. We rule out imprecise estimation of simulation parameters, systematic errors in experimental barrier calibration, and shot-to-shot atom number fluctuations as causes of the discrepancy. However our model does not account for technical noise on the trapping lasers, which may have enhanced the superflow decay in the experiment. For the intermediate temperatures studied in the experiment, we also observe some discrepancy in the sensitivity of the decay timescale to small changes in the barrier height, which may be due to the breakdown of our model's validity in this regime.

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Reservoir interactions during Bose-Einstein condensation: Modified critical scaling in the Kibble-Zurek mechanism of defect formation

Cited by 14 publications

References 45 publications

Reservoir interactions of a vortex in a trapped three-dimensional Bose-Einstein condensate

Reservoir interactions of a vortex in a trapped three-dimensional Bose-Einstein condensate

Superflow decay in a toroidal Bose gas: The effect of quantum and thermal fluctuations

Superflow decay in a toroidal Bose gas: The effect of quantum and thermal fluctuations

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