# -symmetric photonic quantum systems with gain and loss do not exist

@article{Scheel2018symmetricPQ, title={-symmetric photonic quantum systems with gain and loss do not exist}, author={S. Scheel and Alexander Szameit}, journal={Europhysics Letters}, year={2018}, volume={122} }

We discuss the impact of gain and loss on the evolution of photonic quantum states and find that -symmetric quantum optics in gain/loss systems is not possible. Within the framework of macroscopic quantum electrodynamics we show that gain and loss are associated with non-compact and compact operator transformations, respectively. This implies a fundamentally different way in which quantum correlations between a quantum system and a reservoir are built up and destroyed.

## 53 Citations

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