Collective magnetism of atomic momentum states

TL;DR

This paper investigates collective magnetism in a scalar bosonic quantum gas with two laser-coupled momentum modes, revealing interaction-dependent responses and symmetry breaking, with implications for quantum sensing.

Contribution

It demonstrates the emergence of collective magnetism and symmetry breaking in laser-coupled momentum states of a quantum gas, highlighting potential for quantum sensing applications.

Findings

Interaction increases enhance ground state magnetization response.

Evidence of Z2 symmetry breaking in the ground state.

Potential for momentum state squeezing in quantum sensing.

Abstract

Organization and ordering from interactions in many-body systems underlies our understanding of phases of classical and quantum matter. Magnetism has played a particularly foundational role in the study of many-body phases. Here, we explore the collective magnetism that emerges from two laser-coupled momentum modes of a scalar bosonic quantum gas. We employ adiabatic state preparation and explore the collective magnetization response to an applied bias potential, finding that the relative increase of interactions leads to an enhanced and muted response for the ground state and excited state, respectively. We further find evidence for significant $Z_2$ symmetry breaking of the sample magnetization for the ground state, consistent with the expected beyond-mean-field behavior. These results suggest that the nonlinear interactions of scalar Bose condensates could provide a simple, direct path towards the squeezing of momentum states for quantum sensing.