Decaying superfluid turbulence near an anomalous non-thermal fixed point

Abstract

We investigate anomalously slow coarsening in a dilute two-dimensional (2d) superfluid closed with respect to particle and energy exchange with the environment. The dynamics is demonstrated to be closely connected to both, a non-thermal fixed point (NTFP) in a far-from-equilibrium quantum system, and to Kraichnan-Kolmogorov turbulence. During a universal dynamical regime associated with an anomalous NTFP, vortex dynamics are understood to be governed by three-vortex collisions that trigger vortex-antivortex annihilation events, leading to a subdiffusive decay of the vortex density and thus growth of the characteristic inter-defect length scale, ${\ell }_{\text{v}}\sim t^{\beta }$ with $\beta \approx 1/5$. It is found that, during the same time when this power law in time is seen, the moments of the superfluid velocity circulation $\Gamma$ around an area of spatial extent $r$ exhibit power-law scaling ${\Gamma }^2(r)\sim r^{8/3}$, in agreement with Kraichnan-Kolmogorov predictions for an inverse energy cascade in the inertial range, in a driven-open setting. Moreover, in high-order moments, intermittent deviations from linear scaling ${\Gamma }^{2p}(r)\sim [{\Gamma }^2(r){]}^p$ are observed that are consistent with bifractal intermittency corrections previously measured in fully developed classical turbulence. These results establish a quantitative link between decaying quantum turbulence in a closed superfluid and universal dynamics near a non-thermal fixed point. Notably, the subdiffusive decay exponent $\beta \approx 1/5$ deviates significantly from values reported for classical systems.

14 pages, 11 figures

References in corpus (28)

• Dynamics and statistical mechanics of ultra-cold Bose gases using c-field techniques
• Introduction to quantum turbulence
• Non-thermal fixed points: effective weak-coupling for strongly correlated systems far from equilibrium
• Relaxation of superfluid turbulence in highly oblate Bose-Einstein condensates
• Quantum and quasiclassical types of superfluid turbulence
• Nonthermal fixed points and the functional renormalization group
• Critical Dynamics of a Two-dimensional Superfluid near a Non-Thermal Fixed Point
• Quantum Turbulence
• Generation and Decay of Two-Dimensional Quantum Turbulence in a Trapped Bose-Einstein Condensate
• Universal dynamics of a turbulent superfluid Bose gas
• Non-Thermal Fixed Point in a Holographic Superfluid
• Bi-directional universal dynamics in a spinor Bose gas close to a non-thermal fixed point
• Universality class of a spinor Bose-Einstein condensate far from equilibrium
• Universal dynamics and non-thermal fixed points in quantum fluids far from equilibrium
• Universal dynamics of rogue waves in a quenched spinor Bose condensate
• Observation of subdiffusive dynamic scaling in a driven and disordered Bose gas
• Universal Vortex Statistics and Stochastic Geometry of Bose-Einstein Condensation
• Observation of Relaxation Stages in a Nonequilibrium Closed Quantum System: Decaying Turbulence in a Trapped Superfluid
• Universal Coarsening in a Homogeneous Two-Dimensional Bose Gas
• Anomalous scaling at non-thermal fixed points of the sine-Gordon model
• Detecting defect dynamics in relativistic field theories far from equilibrium using topological data analysis
• A universal speed limit for spreading of coherence
• Double sine-Gordon class of universal coarsening dynamics in a spin-1 Bose gas
• Kelvin waves in nonequilibrium universal dynamics of relativistic scalar field theories
• Dynamics of the forward vortex cascade in two-dimensional quantum turbulence
• Fundamental connection between temperature-quenched 2D superfluids and 2D quantum turbulence
• Anomalous non-thermal fixed point in a quasi-two-dimensional dipolar Bose gas
• Decay of two-dimensional superfluid turbulence over pinning surface