Macroscopic Resonant Tunneling in the Presence of Low Frequency Noise

TL;DR

This paper presents a theory for macroscopic resonant tunneling in flux qubits affected by low-frequency noise, showing how tunneling rates reveal noise characteristics and temperature.

Contribution

It introduces a model linking flux tunneling resonances with low-frequency noise features, enabling noise diagnostics in SQUID qubits.

Findings

Resonant tunneling peaks are shaped by low-frequency flux noise.

The shape and position of peaks reflect noise properties.

Noise-induced effects reveal the temperature and quantum nature of the noise source.

Abstract

We develop a theory of macroscopic resonant tunneling of flux in a double-well potential in the presence of realistic flux noise with significant low-frequency component. The rate of incoherent flux tunneling between the wells exhibits resonant peaks, the shape and position of which reflect qualitative features of the noise, and can thus serve as a diagnostic tool for studying the low-frequency flux noise in SQUID qubits. We show, in particular, that the noise-induced renormalization of the first resonant peak provides direct information on the temperature of the noise source and the strength of its quantum component.