Driving-Induced Symmetry Breaking in the Spin-Boson System

TL;DR

This paper demonstrates that harmonic driving can induce symmetry breaking and localization in a dissipative two-state quantum system, with potential experimental applications in superconducting and magnetic systems.

Contribution

It reveals that driving-induced localization and symmetry breaking occur universally in the spin-boson system, independent of dissipation details, when modulating bias and tunneling at specific frequencies.

Findings

Long-time localization occurs under harmonic modulation of bias and tunneling.

Symmetry breaking is universal, not dependent on dissipation mechanisms.

Experimental candidates include rf SQUIDs and magnetic molecular clusters.

Abstract

A symmetric dissipative two-state system is asymptotically completely delocalized independent of the initial state. We show that driving-induced localization at long times can take place when both the bias and tunneling coupling energy are harmonically modulated. Dynamical symmetry breaking on average occurs when the driving frequencies are odd multiples of some reference frequency. This effect is universal, as it is independent of the dissipative mechanism. Possible candidates for an experimental observation are flux tunneling in the variable barrier rf SQUID and magnetization tunneling in magnetic molecular clusters.