The velocity circulation, a measure of the rotation of a fluid within a closed path, is a fundamental observable in classical and quantum flows. It is indeed a Lagrangian invariant in inviscid classical fluids. In quantum flows, circulation is …

In this work we aim at studying numerically the dynamics of an immiscible and finite-size impurity in a quantum fluid at finite temperature. Its dynamics is characterized by means of numerical simulations of the Fourier truncated Gross-Pitaevskii …

Finite-temperature quantum turbulence is often described in terms of two immiscible fluids that can flow with a nonzero-mean relative velocity. Such out-of-equilibrium state is known as counterflow superfluid turbulence. We report here the emergence …

The three-dimensional visualisation above shows a close up of the initial condition used in this work. The red low-density isosurface correspond to quantum vortex lines whereas the greenish rendering are density fluctuations about the bulk value. Remarkably, due to non-local interactions and highly the helical properties of the flow, helical fluctuations of density are observed unlike standard simulations of the Gross-Pitaevskii model.
Incompressible kinetic energy spectrum The figure above displays the kinetic energy spectrum resulting form this initial condition.

Quantum vortices are one of the most important excitations of a superfluid. Such vortices behaves in many aspects as they classical counterpart. They reconnect changing the topology of the flow and transferring energy along scales. We have recently observed that in quantum fluids, there is a manifest irreversibility in the process. Using numerical simulations of the Gross-Pitaevskii model and developing a matching theory we have been able to characterise the momentum and energy exchanges between vortices and density waves.

We statistically study vortex reconnections in quantum fluids by evolving different realizations of vortex Hopf links using the Gross–Pitaevskii model. Despite the time reversibility of the model, we report clear evidence that the dynamics of the …

In a concurrent work, Villois et al. [Phys. Rev. Lett. 125, 164501 (2020)] reported the evidence that vortex reconnections in quantum fluids follow an irreversible dynamics, namely, vortices separate faster than they approach; such time asymmetry is …

Particles are used in superfluid to visualise quantum vortices, they get trapped inside vortices, and we can follow their dynamics. Quantum vortices can reconnect, and particles are an essential tool to study the process.

Reconnections between quantum vortex filaments in presence of trapped particles are investigated using numerical simulations of the Gross--Pitaevskii equation. Particles are described with classical degrees of freedom and modeled as highly repulsive …

The evolution of a turbulent tangle of quantum vortices in the presence of finite-size active particles is studied by means of numerical simulations of the Gross-Pitaevskii equation. Particles are modeled as potentials depleting the superfluid and …