Ladder of Loschmidt anomalies in the deep strong-coupling regime of a qubit-oscillator system

TL;DR

This paper reveals a pattern of singularity-like structures in the deep strong-coupling regime of qubit-oscillator systems, indicating potential new dynamical phase transitions that could impact quantum information processing.

Contribution

It identifies and characterizes regular Loschmidt anomalies in the quantum Rabi model at strong coupling, suggesting novel dynamical phase transitions.

Findings

Discovery of singularity-like structures in Loschmidt amplitude

Identification of conditions for state orthogonalization at specific times

Implications for quantum information processing strategies

Abstract

We uncover a remarkably regular array of singularity-like structures within the deep strong-coupling limit of qubit-oscillator (e.g. light-matter) systems described by the quantum Rabi model, as a function of time and coupling strength. These non-analytic anomalies in the Loschmidt amplitude (echoes) suggest the existence of new forms of dynamical phase transition within this deep strong-coupling regime. The key feature whereby the initial state collapses into orthogonal states at select values of the interaction strength and select times, may be used to enhance - or attack - quantum information processing or computation schemes that rely on removing - or retaining - a given quantum state.