Second Josephson oscillations

TL;DR

This paper investigates a four-mode Bose-Hubbard model with differing tunneling rates, revealing two slow Josephson oscillations, including a heat exchange mode akin to second sound, expanding understanding of mesoscopic quantum systems.

Contribution

It demonstrates that the low-frequency dynamics involve two Josephson oscillations, not just one, and identifies a heat exchange mode similar to second sound.

Findings

Discovery of two slow Josephson oscillations in the model

Identification of a heat exchange mode analogous to second sound

Extension of mesoscopic quantum system understanding

Abstract

As a model for mesoscopic quantum systems in thermal contact, we consider a four-mode Bose-Hubbard model with two greatly differing tunneling rates. By a series of Holstein-Primakoff transformations we show that the low-frequency dynamics of this system consists in general of two slow Josephson oscillations, rather than the single slow mode predicted by linear Bogoliubov theory. We identify the second slow Josephson oscillation as a heat exchange mode analogous to second sound.