Persistent currents and quantised vortices in a polariton superfluid

Hydrodynamic nucleation of vortices and solitons in a resonantly excited polariton superfluid

We present a theoretical study of the hydrodynamic properties of a quantum gas of exciton-polaritons in a semiconductor microcavity under a resonant laser excitation. The effect of a spatially extended defect on the superfluid flow is investigated as a function of the flow speed. The processes that are responsible for the nucleation of vortices and solitons in the wake of the defect are characterized, as well as the regimes where the superfluid flow remains unperturbed. Specific features due to the non-equilibrium nature of the polariton fluid are put in evidence.

Dissipative solitons and vortices in polariton superfluids

We examine spatial localisation and dynamical stability of Bose-Einstein condensates of exciton-polaritons in microcavities under the condition of off-resonant spatially inhomogeneous optical pumping both with and without a harmonic trapping potential. We employ the open-dissipative Gross-Pitaevskii model for describing an incoherently pumped polariton condensate coupled to an exciton reservoir, and reveal that spatial localisation of the steady-state condensate occurs due to the effective self-trapping created by the polariton flows supported by the spatially inhomogeneous pump, regardless of…

Interaction between active particles and quantum vortices leading to Kelvin wave generation

One of the main features of superfluids is the presence of topological defects with quantised circulation. These objects are known as quantum vortices and exhibit a hydrodynamic behaviour. Nowadays, particles are the main experimental tool used to visualise quantum vortices and to study their dynamics. We use a self-consistent model based on the three-dimensional Gross-Pitaevskii (GP) equation to explore theoretically and numerically the attractive interaction between particles and quantised vortices at very low temperature. Particles are described as localised potentials depleting the superfl…

Turbulence in exciton-polariton condensates

Nonequilibrium condensate systems such as exciton-polariton condensates are capable of supporting a spontaneous vortex nucleation. The spatial inhomogeneity of pumping field or/and disordered potential creates velocity flow fields that may become unstable to vortex formation. This letter considers ways in which turbulent states of interacting vortices can be created. It is shown that by combining just two pumping intensities it is possible to create a superfluid turbulence state of well-separated vortices, a strong turbulence state of de-structured vortices, or a weak turbulence state in which…

Annular Vortex Chain in a Resonantly Pumped Polariton Superfluid

We report the formation of a ring-shaped array of vortices after injection of angular momentum in a polariton superfluid. The angular momentum is injected by a $\ell= 8$ Laguerre-Gauss beam, whereas the global rotation of the fluid is hindered by a narrow Gaussian beam placed at its center. In the linear regime a spiral interference pattern containing phase defects is visible. In the nonlinear (superfluid) regime, the interference disappears and the vortices nucleate as a consequence of the angular momentum quantization. The radial position of the vortices evolves freely in the region between …

Critical velocities in superfluids and the nucleation of vortices

The problem of critical velocities in superfluids, that is the comprehension of superfluidity breakdown by flow, has been long standing. One difficulty stems from the existence of several breakdown mechanisms. A major advance has come from the observation of single $2π$ phase slips, which arise from the nucleation of quantised vortices, that is, their creation {\it ex nihilo}. The statistical properties of the nucleation process in both the thermal regime and the quantum regime are identified and analysed: vortex nucleation provides a well-documented case of macroscopic quantum tunnelling (MQT…

Turbulent superfluid profiles in a counterflow channel

We have developed a two-dimensional model of quantised vortices in helium II moving under the influence of applied normal fluid and superfluid in a counterflow channel. We predict superfluid and vortex-line density profiles which could be experimentally tested using recently developed visualization techniques.

Anderson's considerations on the flow of superfluid helium: some offshoots

Nearly five decades have elapsed since the seminal 1966 paper of P.W. Anderson on the flow of superfluid helium, $^4$He at that time. Some of his "Considerations" -- the role of the quantum phase as a dynamical variable, the interplay between the motion of quantised vortices and potential superflow, its incidence on dissipation in the superfluid and the appearance of critical velocities, the quest for the hydrodynamic analogues of the Josephson effects in helium -- and the way they have evolved over the past half-century are recounted below. But it is due to key advances on the experimental fr…

超流 $^3$He 气凝胶实验作为实验室中子星模拟

Superfluid $^3$He aerogel experiments as a laboratory neutron star analogue

本文通过超流 $^3$He 气凝胶中的涡旋实验，模拟中子星的两种不同涡旋钉扎动力学机制，并证明这些概念可应用于中子星观测分析。

量子涡旋在正常流体中留下宏观特征

Quantum vortices leave a macroscopic signature in the normal fluid

该研究通过数值模拟揭示超流氦II中量子涡旋线在正常流体中产生宏观尾流，证明正常流体流动可描述为均匀流与尾流叠加，导致非经典速度统计，并可能解释近期实验发现。