Vortex motion in Fermi superfluids and the Callan-Harvey effect

М. А. Силаев

Lucas Levrouw, Hiromitsu Takeuchi, Jacques Tempere

Григорий Ефимович Воловик

Abstract There are four forces acting on a vortex moving with respect to normal and superfluid components of the liquid: three reactive forces (Magnus, Iordanskii, and Kopnin forces) and the Stokes friction force. The Iordanskii force comes from the analog of the gravitational Aharonov–Bohm effect and are discussed later in the book. The Kopnin or spectral flow force appears only in fermionic superfluids. This chapter discusses the Kopnin force acting on a singular vortex. The origin of this force is the phenomenon of chiral anomaly, but as distinct from the force acting on continuous vortex discussed in Chapter 18, the Adler–Bell–Jackiw equation for chiral anomaly is not applicable. The anomaly is now related to the spectral flow of fermion zero modes in the vortex core, which is caused by motion of the vortex with respect to the normal component. The spectral flow leads to generation of linear momentum by a vortex core, which is then transferred to the normal component. This process is similar to the generation of baryonic charge by the cores of cosmic strings and serves as the analog of Callan–Harvey mechanism of cancellation of anomalies. The temperature dependence of the spectral flow force is obtained from solution of kinetic equation for fermion zero modes. The resulting force acting on a vortex has been measured in experiments on vortex dynamics in 3He-B. Existence of two forces in addition to conventional Magnus and friction forces — Iordanskii and Kopnin forces – has been verified.

Masahiko Machida, Tomio Koyama, Yoji Ohashi

Nicolai Gayle Nygaard, Georg M. Bruun, David L. Feder +2 more

Andrea Richaud, Matteo Caldara, Massimo Capone +2 more

Quantum vortices are commonly described as funnel-like objects around which the superfluid swirls, and their motion is typically modeled in terms of massless particles. Here we show that in Fermi superfluids the normal component confined in the vortex core provides the vortex with a finite inertial mass. This inertia imparts an unambiguous signature to the dynamic behavior of vortices, specifically manifesting as small-amplitude transverse oscillations which remarkably follow the prediction of a simple point-like model supplemented by an effective mass. We demonstrate this phenomenon through large-scale time-dependent simulations of Fermi superfluids across a wide range of interaction parameters, at both zero and finite temperatures, and for various initial conditions. Our findings pave the way for the exploration of inertial effects in superfluid vortex dynamics.