Noise Correlations of Hard-core Bosons: Quantum Coherence and Symmetry Breaking

TL;DR

This paper investigates noise correlations in hard-core bosons, revealing limitations of spin model mappings and identifying new experimental signatures of the Mott phase related to quantum coherence and symmetry breaking.

Contribution

It demonstrates that standard spin-1/2 XY models cannot fully capture noise correlations in hard-core bosons due to virtual states, highlighting particle-hole symmetry breaking.

Findings

Noise correlations reveal particle-hole symmetry breaking in HCB systems.

Distinctive signatures of the Mott phase are identified in noise correlation measurements.

Standard spin models fail to account for multiply occupied virtual states in HCBs.

Abstract

Noise correlations, such as those observable in the time of flight images of a released cloud, are calculated for hard-core bosonic (HCB) atoms. We find that the standard mapping of HCB systems onto spin-1/2 XY models fails in application to computation of noise correlations due to the contribution of multiply occupied virtual states in HCB systems. Such states do not exist in spin models. An interesting manifestation of such states is the breaking of particle-hole symmetry in HCB. We use noise correlations to explore quantum coherence of strongly correlated bosons in the fermionized regime with and without external parabolic confinement. Our analysis points to distinctive new experimental signatures of the Mott phase.