Spontaneous symmetry breaking induced by quantum monitoring

TL;DR

This paper explores how continuous quantum measurements can induce spontaneous symmetry breaking by back-action, allowing control over the symmetry-breaking pattern and resulting topological features.

Contribution

It introduces a novel mechanism for SSB driven by quantum monitoring, expanding understanding of measurement-induced symmetry phenomena.

Findings

Quantum monitoring induces SSB through measurement back-action.

Monitoring different observables tailors the vacuum manifold topology.

Measurement process influences the pattern of symmetry breaking and defect formation.

Abstract

Spontaneous symmetry breaking (SSB) is responsible for structure formation in scenarios ranging from condensed matter to cosmology. SSB is broadly understood in terms of perturbations to the Hamiltonian governing the dynamics or to the state of the system. We study SSB due to quantum monitoring of a system via continuous quantum measurements. The acquisition of information during the measurement process induces a measurement back-action that seeds SSB. In this setting, by monitoring different observables, an observer can tailor the topology of the vacuum manifold, the pattern of symmetry breaking and the nature of the resulting domains and topological defects.