Sound Emission in Vortex Reconnections made the Cover of PRL
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. The main results have been published in Physical Review Letters (Villois et al. 2020) and detailed calculation on Physical Review Fluids (Proment and Krstulovic 2020).
The movie below shows a numerical simulation of the Gross-Pitaevskii model. A Hopf link vortex (two chained rings) evolves in time and reconnect. At the moment of reconnection, a clear pulse is emitted in the upwards direction.