Quantum correlations in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>PT</mml:mi> </mml:math> -symmetric systems
Federico Roccati, Salvatore Lorenzo, G Massimo Palma, Gabriel T Landi, Matteo Brunelli, Francesco Ciccarello
Abstract
Abstract We study the dynamics of correlations in a paradigmatic setup to observe <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi mathvariant="script">PT</mml:mi> </mml:math> -symmetric physics: a pair of coupled oscillators, one subject to a gain one to a loss. Starting from a coherent state, quantum correlations (QCs) are created, despite the system being driven only incoherently, and can survive indefinitely. Both total and QCs exhibit different scalings of their long-time behavior in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi mathvariant="script">PT</mml:mi> </mml:math> -broken/unbroken phase and at the exceptional point (EP). In particular, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi mathvariant="script">PT</mml:mi> </mml:math> symmetry breaking is accompanied by non-zero stationary QCs. This is analytically shown and quantitatively explained in terms of entropy balance. The EP in particular stands out as the most classical configuration, as classical correlations diverge while QCs vanish.