Dynamical quantum phase transitions in a spinor Bose-Einstein condensate and criticality enhanced quantum sensing

TL;DR

This paper demonstrates how dynamical quantum phase transitions in spinor Bose-Einstein condensates can reveal both ground and excited-state quantum criticality and enhance quantum sensing capabilities.

Contribution

It uncovers the connection between equilibrium and nonequilibrium phase transitions in spinor condensates using quantum Fisher information.

Findings

Dynamical phase transitions diagnose excited-state quantum phase transitions.

Quantum Fisher information links criticality to quantum sensing.

Enhanced parameter estimation beyond standard quantum limit near critical points.

Abstract

Quantum phase transitions universally exist in the ground and excited states of quantum many-body systems, and they have a close relationship with the nonequilibrium dynamical phase transitions, which however are challenging to identify. In the system of spin-1 Bose-Einstein condensates, though dynamical phase transitions with correspondence to equilibrium phase transitions in the ground state and uppermost excited state have been probed, those taken place in intermediate excited states remain untouched in experiments thus far. Here we unravel that both the ground and excited-state quantum phase transitions in spinor condensates can be diagnosed with dynamical phase transitions. A connection between equilibrium phase transitions and nonequilibrium behaviors of the system is disclosed in terms of the quantum Fisher information. We also demonstrate that near the critical points parameter estimation beyond standard quantum limit can be implemented. This work not only advances the exploration of excited-state quantum phase transitions via a scheme that can immediately be applied to a broad class of few-mode quantum systems, but also provides new perspective on the relationship between quantum criticality and quantum enhanced sensing.