Adding energy to a system through transient stirring usually leads more disorder. In contrast, point-like vortices in bounded two-dimensional fluid are predicted reorder above certain energy, forming persistent vortex clusters. Here we realize experimentally these clusters planar superfluid: $^{87}$Rb Bose-Einstein condensate confined an elliptical geometry. We demonstrate that the persist for long times, maintaining superfluid high state far from global equilibrium. Our experiments explore...

We demonstrate an inverse energy cascade in a minimal model of forced 2D quantum vortex turbulence. simulate the Gross-Pitaevskii equation for moving superfluid subject to forcing by stationary grid obstacle potentials, and damping thermal cloud. The injects large amounts into system at scale few healing lengths. A regime is identified where efficiently transported length scales via associated with growth clusters same-circulation vortices, Kolmogorov scaling law kinetic spectrum over...

Despite the prominence of Onsager's point-vortex model as a statistical description 2D classical turbulence, first-principles development for realistic superfluid has remained an open problem. Here we develop mapping system quantum vortices described by homogeneous Gross-Pitaevskii equation (GPE) to model, enabling Monte Carlo sampling vortex microcanonical ensemble. We use this approach survey full range states in superfluid, from vortex-dipole gas at positive temperature...

The Reynolds number provides a characterization of the transition to turbulent flow, with wide application in classical fluid dynamics. Identifying such parameter superfluid systems is challenging due their fundamentally inviscid nature. Performing systematic study cylinder wakes two dimensions, we observe dynamical similarity frequency vortex shedding by cylindrical obstacle. universality wake dynamics revealed expressing frequencies terms an appropriately defined number, Re(s), that...

We investigate two-dimensional turbulence in finite-temperature trapped Bose-Einstein condensates within damped Gross-Pitaevskii theory. Turbulence is produced via circular motion of a Gaussian potential barrier stirring the condensate. systematically explore range parameters and identify three regimes, characterized by injection distinct quantum vortex structures into condensate: (A) periodic dipole injection, (B) irregular mixture dipoles co-rotating clusters, (C) continuous oblique...

We explore the possible regimes of decaying two-dimensional quantum turbulence, and elucidate nature spectral energy transport by introducing a dissipative point-vortex model with phenomenological vortex-sound interactions. The is valid for large system weak dissipation, also systems strong allows us to extract meaningful unambiguous flux associated vortex motion. For dissipation size we find regime hydrodynamic turbulence in which transported spatial scales, resembling phenomenology...

The emergence of coherent rotating structures is a phenomenon characteristic both classical and quantum 2D turbulence. In this work we show theoretically that the vortex emerge in decaying turbulence can approach quasi-classical rigid-body rotation, obeying Feynman rule constant average areal density while remaining spatially disordered. By developing rigorous link between velocity probability distribution kinetic energy spectrum over wavenumber $k$, are associated with $k^3$ power law...

Clustering of like-sign vortices in a planar bounded domain is known to occur at negative temperature, phenomenon that Onsager demonstrated be consequence phase space. In confined superfluid, quantized can support such an ordered phase, provided they evolve as almost isolated subsystem containing sufficient energy. A detailed theoretical understanding the statistical mechanics states thus requires microcanonical approach. Here we develop analytical theory vortex clustering transition neutral...

We experimentally realize a highly tunable superfluid oscillator circuit in quantum gas of ultracold atoms and develop verify simple lumped-element description this circuit. At low currents, we demonstrate that the is accurately described as Helmholtz resonator, fundamental element acoustic circuits. larger breakdown regime heralded by turbulent shedding vortices density waves. Although phase-slip model offers qualitative insights into circuit's resistive behavior, our results indicate...

We experimentally study emergence of microcanonical equilibrium states in the turbulent relaxation dynamics a two-dimensional chiral vortex gas. Same-sign vortices are injected into quasi-two-dimensional disk-shaped atomic Bose-Einstein condensate using range mechanical stirring protocols. The resulting long-time distributions found to be excellent agreement with meanfield Poisson-Boltzmann equation for system describing ensemble at fixed energy $\cal{H}$ and angular momentum $\cal{M}$....

Quantized vortices are fundamental to the two-dimensional dynamics of superfluids, from quantum turbulence phase transitions. However, surface effects have prevented direct observations coherent vortex in strongly interacting systems. Here, we overcome this challenge by confining a thin film superfluid helium at microscale on atomically smooth silicon chip. An on-chip optical microcavity allows laser initiation clusters quasi-two-dimensional and nondestructive observation their decay single...

We report evidence for an enstrophy cascade in large-scale point-vortex simulations of decaying two-dimensional quantum turbulence. Devising a method to generate vortex configurations with kinetic energy narrowly localized near single length scale, the dynamics are found be well characterized by superfluid Reynolds number ${\mathrm{Re}}_{\mathrm{s}}$ that depends only on vortices and initial scale. Under free evolution exhibit features classical cascade, including ${k}^{\ensuremath{-}3}$...

A large ensemble of quantum vortices in a superfluid may itself be treated as novel kind fluid that exhibits anomalous hydrodynamics. Here we consider the dynamics vortex clusters with thermal friction, and present an analytic solution uncovers new universality class out-of-equilibrium dissipative superfluids. We find long-time vorticity distribution is expanding Rankine (i.e.~top-hat distribution) independent initial conditions. This highlights fundamentally different decay process to...

We consider the far-from-equilibrium quantum transport dynamics in a 1D Josephson junction chain of multimode Bose-Einstein condensates. develop theoretical model to examine experiment Labouvie et al. [Phys. Rev. Lett. 115, 050601 (2015)], wherein phenomenon negative differential conductivity (NDC) was reported refilling an initially depleted site within chain. demonstrate that unitary $c$-field description can quantitatively reproduce experimental results over full range tunnel couplings,...

We characterize the mechanisms of vortex pinning in a superfluid thin film described by two-dimensional Gross-Pitaevskii equation. consider "scattering experiment" whereby single flow interacts with circular, uniform potential. By an analogy linear dielectrics, we develop analytical hydrodynamic approximation that predicts trajectories, fixed point and unpinning velocity. then solve equation to validate this model, build phase portrait pinning. identify two different dynamical marked...

The two-dimensional One-Component Plasma (OCP) is a foundational model of the statistical mechanics interacting particles, describing phenomena common to astrophysics, turbulence, and Fractional Quantum Hall Effect (FQHE). Despite an extensive literature, phase diagram 2D OCP still subject some controversy. Here we develop "vortex matter" simulator realize logarithmic-interaction experimentally by exploiting topological character quantized vortices in thin superfluid layer. Precision...

Despite the fundamentally different dissipation mechanisms, many laws and phenomena of classical turbulence equivalently manifest in quantum turbulence. The Reynolds law dynamical similarity states that two objects same geometry across length scales are hydrodynamically equivalent under number, leading to a universal drag coefficient law. In this work we confirm existence superfluid wake, facilitated by nucleation quantized vortices. We numerically study flow range numbers for paradigmatic...

We study the creation and breakdown of a quantized vortex shear layer forming between stationary Bose-Einstein condensate stirred-in persistent current. Once turbulence is established, we characterize progressive clustering vortices, showing that cluster number follows power law decay with time, similar to decaying in other two-dimensional systems. Numerical system demonstrates good agreement experimental data point model includes damping noise. With increasing computational model, observe...