Effects of Resonant Cavity on Macroscopic Quantum Tunneling of Fluxon in Long Josephson Junctions

TL;DR

This paper studies how a high-Q resonant cavity influences macroscopic quantum tunneling of fluxons in long Josephson junctions, showing potential for tuning quantum bits via cavity interactions.

Contribution

It introduces a coupled sine-Gordon model to analyze cavity effects on fluxon tunneling, revealing enhanced tunneling rates and energy splitting due to cavity interactions.

Findings

MQT rate increases with cavity interaction strength.

Energy splitting between ground states grows significantly with cavity parameters.

Resonant cavity can be used to tune Josephson vortex quantum bits.

Abstract

We investigate the effects of high-Q_c resonant cavity on macroscopic quantum tunneling (MQT) of fluxon both from a metastable state to continuum and from one degenerate ground-state of a double-well potential to the other. By using a set of two coupled perturbed sine-Gordon equations, we describe the tunneling processes in linear long Josephson junctions (LJJs) and find that MQT in the resonant cavity increases due to potential renomalization, induced by the interaction between the fluxon and cavity.Enhancement of the MQT rate in the weak-coupling regime is estimated by using the experimantally accessible range of the model parameters. The tunneling rate from the metastable state is found to increase weakly with increasing junction-cavity interaction strength. However, the energy splitting between the two degenerate ground-states of the double-well potential increases significantly with increasing both the interaction strength and frequency of the resonant cavity mode. Finally, we discuss how the resonant cavity may be used to tune the property of Josephson vortex quantum bits.