Theory of light detection in the presence of feedback

J. H. Shapiro, G. Saplakoglu, Seng-Tiong Ho, B. E.A. Saleh, M. C. Teich

Research output: Contribution to journalArticlepeer-review

118 Scopus citations


The usual open-loop quantum and semiclassical theories of light detection are extended to include closed-loop operation in which there is feedback from the detector to the source. It is shown that the unmistakable signatures of nonclassical light associated with open-loop detection, such as sub-shot-noise spectra and sub-Poisson photocounts, do not carry over to closed-loop systems. This behavior is illustrated through quantitatively indistinguishable quantum and semiclassical analyses of two recent closed-loop experiments in which sub-Poisson photocount statistics were produced. It turns out that if the open-loop illumination does not require the use of quantum photodetection theory, then neither does the closed-loop illumination. Conversely, if the open-loop illumination is nonclassical, then the closed-loop behavior must be analyzed quantum mechanically. The use of nonclassical field correlations to obtain light beams that give sub-Poisson open-loop photocounts from these closed-loop arrangements is discussed and generalized into a synthesis procedure for producing light beams with arbitrary open-loop photocount statistics.

Original languageEnglish (US)
Pages (from-to)1604-1620
Number of pages17
JournalJournal of the Optical Society of America B: Optical Physics
Issue number10
StatePublished - Jan 1 1987

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Atomic and Molecular Physics, and Optics


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