Spin-asymmetric Josephson plasma oscillations

TL;DR

This paper proposes that in ultracold Fermi gases, spin-dependent potentials can induce spin-asymmetric Josephson plasma oscillations, offering a new way to observe the unconfirmed spin-asymmetric Josephson effect.

Contribution

It demonstrates theoretically that spin-dependent potentials cause spin-dependent amplitudes in Josephson plasma oscillations without changing the frequency, suggesting a method for experimental detection.

Findings

Spin-dependent potentials lead to spin-dependent oscillation amplitudes.

The Josephson frequency remains the same for both spins.

Detection of these oscillations can confirm the spin-asymmetric Josephson effect.

Abstract

The spin-asymmetric Josephson effect is a proposed quantum-coherent tunnelling phenomenon where Cooper-paired fermionic spin-$\frac{1}{2}$ particles, which are subjected to spin-dependent potentials across a Josephson junction, undergo frequency-synchronized alternating-current Josephson oscillations with spin-dependent amplitudes. Here, in line with present-day techniques in ultracold Fermi gas setups, we consider the regime of small Josephson oscillations and show that the Josephson plasma oscillation amplitude becomes spin-dependent in the presence of spin-dependent potentials while the Josephson plasma frequency is the same for both spin-components. Detecting these spin-dependent Josephson plasma oscillations provides a possible means to establish the yet-unobserved spin-asymmetric Josephson effect with ultracold Fermi gases using existing experimental tools.