Spontaneous PT symmetry breaking of a ferromagnetic superfluid in a gradient field

TL;DR

This paper investigates how a ferromagnetic spinor Bose-Einstein condensate in a magnetic field gradient undergoes a spontaneous PT symmetry breaking phase transition, with implications for high-coherence magnetic sensors.

Contribution

It demonstrates the spontaneous breaking of PT symmetry in a ferromagnetic superfluid due to a magnetic field gradient, revealing a new phase transition mechanism.

Findings

First-order phase transition observed in simulations

Spontaneous PT symmetry breaking in the system

Potential for high-coherence magnetic sensors

Abstract

We consider the interaction of a ferromagnetic spinor Bose-Einstein condensate with a magnetic field gradient. The magnetic field gradient realizes a spin-position coupling that explicitly breaks time-reversal symmetry T and space parity P, but preserves the combined PT symmetry. We observe using numerical simulations, a first-order phase transition spontaneously breaking this re-maining symmetry. The transition to a low-gradient phase, in which gradient effects are frozen out by the ferromagnetic interaction, suggests the possibility of high-coherence magnetic sensors unaffected by gradient dephasing.