Spontaneous breaking of spatial and spin symmetry in spinor condensates

TL;DR

This paper demonstrates how a spinor condensate can spontaneously break both spatial and spin symmetries through quantum fluctuation amplification, revealing detailed mechanisms of symmetry breaking and pattern formation.

Contribution

It provides experimental insights into the simultaneous breaking of spatial and spin symmetries in spinor condensates via parametric amplification of quantum fluctuations.

Findings

Cylindrical spatial symmetry is spontaneously broken at resonances creating vortex-antivortex superpositions.

Phase squeezing prevents spin-symmetry breaking in certain resonances.

Quantum interferences induce spin-dependent density patterns when nondegenerate spin modes are amplified.

Abstract

Parametric amplification of quantum fluctuations constitutes a fundamental mechanism for spontaneous symmetry breaking. In our experiments, a spinor condensate acts as a parametric amplifier of spin modes, resulting in a twofold spontaneous breaking of spatial and spin symmetry in the amplified clouds. Our experiments permit a precise analysis of the amplification in specific spatial Bessel-like modes, allowing for the detailed understanding of the double symmetry breaking. On resonances that create vortex-antivortex superpositions, we show that the cylindrical spatial symmetry is spontaneously broken, but phase squeezing prevents spin-symmetry breaking. If, however, nondegenerate spin modes contribute to the amplification, quantum interferences lead to spin-dependent density profiles and hence spontaneously-formed patterns in the longitudinal magnetization.