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Quantum theory of light and noise polarization in nonlinear optics

Stefan Scheel·Dirk-Gunnar Welsch
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Abstract

We present a consistent quantum theory of the electromagnetic field in nonlinearly responding causal media, with special emphasis on $χ^{(2)}$ media. Starting from QED in linearly responding causal media, we develop a method to construct the nonlinear Hamiltonian expressed in terms of the complex nonlinear susceptibility in a quantum mechanically consistent way. In particular we show that the method yields the nonlinear noise polarization, which together with the linear one is responsible for intrinsic quantum decoherence.

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Stefan Scheel, Dirk-Gunnar Welsch. 2005-08-16. Quantum theory of light and noise polarization in nonlinear optics. https://doi.org/10.1103/physrevlett.96.073601

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