Einstein-Podolsky-Rosen steering of quantum phases in a cavity Bose-Einstein condensate with a single impurity

TL;DR

This paper investigates EPR steering in a cavity BEC with a single impurity, revealing how impurity control can manipulate quantum correlations and witness phase transitions between normal and superradiant phases.

Contribution

It demonstrates the impurity's role as a switch for EPR steering and introduces EPR parameters as indicators of quantum phase transitions in the generalized Dicke model.

Findings

EPR steering varies between one-way and two-way in different phases.

Single impurity can control the direction and type of EPR steering.

EPR parameters can signal quantum phase transitions at critical points.

Abstract

We study Einstein-Podolsky-Rosen (EPR) steering properties of quantum phases in the generalized Dicke model (GDM) generated by a cavity Bose-Einstein condensate (BEC) doped with a single impurity. It is shown that the normal and superradiant phases of the GDM exhibit much rich EPR steerability. In the normal phase, there exist one-way EPR steering from the cavity field (condensed atoms) to condensed atoms (the cavity field). In the superradiant phase, there is either one-way or two-way EPR steering for the cavity field and condensed atoms. It is found that the single impurity can act as a single-atom switch of the EPR steering to control the steering direction of one-way EPR steering and the transition between one-way and two-way EPR steering through switching on or off the impurity-BEC coupling. It is proved that the EPR steering parameters can witness the quantum phase transition (QPT) occurrence through the sudden change of the EPR steering parameters at the critical point of the QPT. Our results open a new way to manipulate macroscopic EPR steering and witness the QPT between the normal phase and the superradiant phase in the GDM through a microscopic impurity atom.