Synthetic dissipation and cascade fluxes in a turbulent quantum gas

Navon, Nir; Eigen, Christoph; Zhang, Jin-Yi; Lopes, Raphaël; Gaunt, Alexander L.; Fujimoto, Kazuya; Tsubota, Makoto; Smith, Robert P.; Hadzibabic, Zoran

doi:10.1126/science.aau6103

Cited by 74 publications

(63 citation statements)

References 41 publications

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“…We note that for our strongest (resonant) drive the gas is turbulent in steady state [49], and the many-body decay of the lowestlying mode provides a stepping stone toward the transfer of energy to higher-lying modes. Thus, our work paves the way for a microscopic understanding of the genesis of a turbulent cascade [49,62], where the energy leakage from the driven discrete lowest-lying mode is sufficiently large to sustain a nonequilibrium steady state. Such a transition from the discrete-state dynamics to a continuum turbulent cascade has recently been theoretically studied in a cosmological context [63].…”

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confidence: 84%

Many-Body Decay of the Gapped Lowest Excitation of a Bose-Einstein Condensate

et al. 2021

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We study the decay mechanism of the gapped lowest-lying axial excitation of a quasipure atomic Bose-Einstein condensate confined in a cylindrical box trap. Owing to the absence of accessible lower-energy modes, or direct coupling to an external bath, this excitation is protected against one-body (linear) decay, and the damping mechanism is exclusively nonlinear. We develop a universal theoretical model that explains this fundamentally nonlinear damping as a process whereby two quanta of the gapped lowest excitation mode couple to a higher-energy mode, which subsequently decays into a continuum. We find quantitative agreement between our experiments and the predictions of this model. Finally, by strongly driving the system below its (lowest) resonant frequency, we observe third-harmonic generation, a hallmark of nonlinear behavior.

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confidence: 84%

Many-Body Decay of the Gapped Lowest Excitation of a Bose-Einstein Condensate

et al. 2021

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“…Similarly, interactions between the condensate and the cloud of uncondensed particles will induce damping of condensate modes, which may help to counteract the Floquet instability. Finally, a particularly intriguing possibility is the induce synthetic dissipation into the system, allowing for a tunable cutoff in the GPE description [20]. However, we expect the effects of realistic physical corrections will also leak into the dynamics of the longer wavelength modes needed to nucleate the bubbles.…”

Section: Nonlinear Dynamicsmentioning

confidence: 99%

Nonlinear dynamics of the cold atom analog false vacuum

Braden

Johnson

Peiris

et al. 2019

J. High Energ. Phys.

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We investigate the nonlinear dynamics of cold atom systems that can in principle serve as quantum simulators of false vacuum decay. The analog false vacuum manifests as a metastable vacuum state for the relative phase in a two-species Bose-Einstein condensate (BEC), induced by a driven periodic coupling between the two species. In the appropriate low energy limit, the evolution of the relative phase is approximately governed by a relativistic wave equation exhibiting true and false vacuum configurations. In previous work, a linear stability analysis identified exponentially growing short-wavelength modes driven by the time-dependent coupling. These modes threaten to destabilize the analog false vacuum. Here, we employ numerical simulations of the coupled Gross-Pitaevski equations (GPEs) to determine the non-linear evolution of these linearly unstable modes. We find that unless a physical mechanism modifies the GPE on short length scales, the analog false vacuum is indeed destabilized. We briefly discuss various physically expected corrections to the GPEs that may act to remove the exponentially unstable modes. To investigate the resulting dynamics in cases where such a removal mechanism exists, we implement a hard UV cutoff that excludes the unstable modes as a simple model for these corrections. We use this to study the range of phenomena arising from such a system. In particular, we show that by modulating the strength of the time-dependent coupling, it is possible to observe the crossover between a second and first order phase transition out of the false vacuum.

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“…Hence, approaches other than the power-law behavior have been employed to overcome these issues. Energy and particle fluxes have been used in simulations [ 7 , 8 ] and experiments [ 9 , 10 ] as alternative methods to investigate and characterize quantum turbulence.…”

Section: Introductionmentioning

confidence: 99%

Entropy of a Turbulent Bose-Einstein Condensate

Madeira

García-Orozco

Santos

et al. 2020

Entropy

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Quantum turbulence deals with the phenomenon of turbulence in quantum fluids, such as superfluid helium and trapped Bose-Einstein condensates (BECs). Although much progress has been made in understanding quantum turbulence, several fundamental questions remain to be answered. In this work, we investigated the entropy of a trapped BEC in several regimes, including equilibrium, small excitations, the onset of turbulence, and a turbulent state. We considered the time evolution when the system is perturbed and let to evolve after the external excitation is turned off. We derived an expression for the entropy consistent with the accessible experimental data, which is, using the assumption that the momentum distribution is well-known. We related the excitation amplitude to different stages of the perturbed system, and we found distinct features of the entropy in each of them. In particular, we observed a sudden increase in the entropy following the establishment of a particle cascade. We argue that entropy and related quantities can be used to investigate and characterize quantum turbulence.

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Synthetic dissipation and cascade fluxes in a turbulent quantum gas

Cited by 74 publications

References 41 publications

Many-Body Decay of the Gapped Lowest Excitation of a Bose-Einstein Condensate

Many-Body Decay of the Gapped Lowest Excitation of a Bose-Einstein Condensate

Nonlinear dynamics of the cold atom analog false vacuum

Entropy of a Turbulent Bose-Einstein Condensate

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