Beyond superfluidity in non-equilibrium Bose–Einstein condensates

Pinsker, Florian

doi:10.1088/1367-2630/aa9561

Cited by 4 publications

(2 citation statements)

References 64 publications

(180 reference statements)

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“…and can be estimated by considering the fluid of light moving with velocity v, and a static obstacle with a [40][41][42]. Furthermore, we also neglect the absorption of the medium and consider that the nonlinear response is in the Kerr regime (I f ≪ I sat ), such that ∆n total ≈ −I f /I sat .…”

Section: Breakdown Of the Superfluid Regime And The Development Of Tu...mentioning

confidence: 99%

Towards the experimental observation of turbulent regimes and the associated energy cascades with paraxial fluids of light

et al. 2022

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The propagation of light in nonlinear optical media has been widely used as a tabletop platform for emulating quantum-like phenomena due to their similar theoretical description to quantum fluids. These fluids of light are often used to study 2-dimensional phenomena involving superfluid-like flows, yet turbulent regimes still remain underexplored. In this work, we study the possibility of creating 2-dimensional turbulent phenomena and probing their signatures in the kinetic energy spectrum. To that end, we emulate and disturb a fluid of light with an all-optical defect using the propagation of two beams in a photorefractive crystal. Our experimental results show that the superfluid regime of the fluid of light breaks down at a critical velocity at which the defect starts to exert a drag force on the fluid, in accordance with the theoretical and numerical predictions. Furthermore, in this dissipative regime, nonlinear perturbations are excited on the fluid that can decay into vortex structures and thus precede a turbulent state. Using the off-axis digital holographic method, we reconstructed the complex description of the output fluids and calculated the incompressible component of the kinetic energy. With these states, we observed the expected power law that characterizes the generated turbulent vortex dipole structures. The findings enclosed in this manuscript align with the theoretical predictions for the vortex structures of 2-dimensional quantum fluids and thus may pave the way to the observation of other distinct hallmarks of turbulent phenomena, such as distinct turbulent regimes and their associated power laws and energy cascades.

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Section: Breakdown Of the Superfluid Regime And The Development Of Tu...mentioning

confidence: 99%

Towards the experimental observation of turbulent regimes and the associated energy cascades with paraxial fluids of light

et al. 2022

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“…In this context, differently from the calculation of the drag force for a non-equilibrium condensate in Ref. [28] based on the complex GrossPitaevskii (GP) theory, our model fully includes the role of the non-resonant reservoir by solving driven-dissipative GP equation coupled to a rate equation; differently from Ref. [29,30] of calculating the drag force of nonresonantly pumped polariton condensate prepared in the gapless region of the Bogoliubov modes, we study the drag force of non-resonantly pumped polariton condensate in the gapped region of the Bogoliubov modes.…”

Section: Introductionmentioning

confidence: 97%

Drag force of a exciton-polariton condensate under non-resonant pumping

He,

Liang

2020

Preprint

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Exciton-polariton condensate in semiconductor microcavities constitute a novel kind of nonequilibrium superfluid. In a recent experiment [P. Stepanov, et. al., Nat. Commun. 10, 1038(2019], the dispersion relation of collective excitations in a polariton condensate under the resonant pumping has been investigated with the emphasis on the role of reservoir of long-lived excitons in determining the superfluidity. Inspired by such an experimental advance, we study the superfluidity of a exciton-polaritonn condensate under non-resonant pumping by calculating the drag force exerted on a classical impurity moving in a polariton condensate. For a non-resonant pumped polariton condensate prepared in the gapped phase, due to the reservoir's modes, the drag force can be large when the velocity of the impurity is small. Besides, as the velocity increases, the drag force can decrease. For not very large velocity, the drag force is enhanced if the condensate is tuned to be more dissipative. When the condensate is close to the transition point between the gapped phase and the gapless one, the drag force is similar to that of the equilibrium superfluid. Our present work reveals the effects of the reservoir's modes on the superfluidity properties of a polariton condensate with the non-resonant pumping.

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Classical analogies for the force acting on an impurity in a Bose–Einstein condensate

et al. 2020

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We study the hydrodynamic forces acting on a small impurity moving in a two-dimensional Bose–Einstein condensate at non-zero temperature. The condensate is modelled by the damped-Gross Pitaevskii (dGPE) equation and the impurity by a Gaussian repulsive potential coupled to the condensate. For weak coupling, we obtain analytical expressions for the forces acting on the impurity, and compare them with those computed through direct numerical simulations of the dGPE and with the corresponding expressions for classical forces. For non-steady flows, there is a time-dependent force dominated by inertial effects and which has a correspondence in the Maxey–Riley theory for particles in classical fluids. In the steady-state regime, the force is dominated by a self-induced drag. Unlike at zero temperature, where the drag force vanishes below a critical velocity, at low temperatures the impurity experiences a net drag even at small velocities, as a consequence of the energy dissipation through interactions of the condensate with the thermal cloud. This dissipative force due to thermal drag is similar to the classical Stokes’ drag. There is still a critical velocity above which steady-state drag is dominated by acoustic excitations and behaves non-monotonically with impurity’s speed.

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Beyond superfluidity in non-equilibrium Bose–Einstein condensates

Cited by 4 publications

References 64 publications

Towards the experimental observation of turbulent regimes and the associated energy cascades with paraxial fluids of light

Towards the experimental observation of turbulent regimes and the associated energy cascades with paraxial fluids of light

Drag force of a exciton-polariton condensate under non-resonant pumping

Classical analogies for the force acting on an impurity in a Bose–Einstein condensate

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