Nonlinear Phenomena in Complex Systems, 1999, Vol.2, No.4, pp.72--77

NONLINEAR PHENOMENA IN COMPLEX SYSTEMS
An Interdisciplinary Journal

1999, Volume 2, Number 4, pp.72--77

Quantum Theory of Photodetection in the Presence of Feedback.
S. Ya. Kilin and D. B. Horoshko

We develop a theory of photodetection in the presence of feedback valid for arbitrary time delay in the feedback loop and any degree of field fluctuation. As a result we obtain an expression for the in-loop photocurrent autocorrelation function which differs from the traditional one by replacing the delta-function by the Green function of the feedback loop. We discuss two main consequences of the new formula: frequency-dependent standard quantum limit in the presence of feedback, and the violation of statistical equivalence between the photon flux and the photocurrent in the feedback loop.

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