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arXiv · 1905.07348

Eternal life of entropy in non-Hermitian quantum systems

Andreas Fring·Thomas Frith
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Abstract

We find a new effect for the behaviour of Von Neumann entropy. For this we derive the framework for describing Von Neumann entropy in non-Hermitian quantum systems and then apply it to a simple interacting PT symmetric bosonic system. We show that our model is well defined even in the PT broken regime with the introduction of a time-dependent metric and that it displays three distinct behaviours relating to the PT symmetry of the original time-independent Hamiltonian. When the symmetry is unbroken, the entropy undergoes rapid decay to zero (so-called "sudden death") with a subsequent revival. At the exceptional point it decays asymptotically to zero and when the symmetry is spontaneously broken it decays asymptotically to a finite constant value ("eternal life").

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Andreas Fring, Thomas Frith. 2019-05-17. Eternal life of entropy in non-Hermitian quantum systems. https://doi.org/10.1103/physreva.100.010102

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