Theory for Photon-Assisted Macroscopic Quantum Tunneling in a Stack of Intrinsic Josephson Junctions

TL;DR

This paper develops a theoretical model for photon-assisted macroscopic quantum tunneling in stacked intrinsic Josephson junctions, revealing that the escape rate scales with the square of the number of junctions, aligning with experimental observations.

Contribution

The paper introduces a new theory describing photon-assisted MQT in coupled Josephson junctions, highlighting the N^2 scaling of the escape rate and clarifying energy-level quantization in collective modes.

Findings

Escape rate scales as N^2 in multi-junction systems.

Theory aligns with recent experimental results in Bi-2212.

Excitation of longitudinal plasma modes influences tunneling behavior.

Abstract

We propose a theory for photon-assisted macroscopic quantum tunneling (MQT) in a stack of capacitively-coupled intrinsic Josephson junctions in which the longitudinal Josephson plasma, i.e., longitudinal collective phase oscillation modes, is excited. The scheme of energy-level quantization in the collective oscillatory states is clarified in the $N$-junction system. When the MQT occurs from the single-plasmon states excited by microwave irradiation in the multi-photon process to the uniform voltage state, our theory predicts that the escape rate is proportional to $N^2$. This result is consistent with the recent observation in Bi-2212 intrinsic Josephson junctions.