Quantum Simulation of Energy Bifurcation and Z_2-Symmetry Restoration in Macroscopic Quantum Tunneling

Abstract:Macroscopic quantum tunneling (MQT), a cornerstone of Leggett's program, is deeply linked with instanton physics, yet its experimental verification remains elusive. This Perspective demonstrates that the quantum Rabi model manifests observable, instanton-like effects via quantum simulation. In the MQT regime, qubit-boson interactions drive Polyakov's energy bifurcation, governing tunneling and spontaneous symmetry breaking. Mapping the quantum Rabi model onto an effective double-well potential reveals that while tunneling suppression induces spontaneous symmetry breaking, instanton-like contributions act to restore it. This mechanism enables experimental access to the classical Euclidean action of an effective instanton-like particle, offering a route to probe non-perturbative phenomena.

13 pages, 15 figures. I have made some minor additions and revisions to the explanation, and added references

arXiv:2605.23413 [quant-ph]

(or arXiv:2605.23413v2 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2605.23413 Focus to learn more arXiv-issued DOI via DataCite

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