Probabilistic phase-insensitive optical squeezer in compliance with causality

C. N. Gagatsos, E. Karpov, N. J. Cerf

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


A non-trace-preserving map describing a probabilistic but heralded noiseless linear amplifier has recently been proposed and experimentally demonstrated. Here, we exhibit another remarkable feature of this peculiar transformation, namely its ability to serve as a universal single-mode squeezer regardless of the quadrature that is initially squeezed. Hence, it acts as a heralded phase-insensitive optical squeezer, conserving the signal-to-noise ratio just as a phase-sensitive optical amplifier but for all quadratures at the same time, which may offer interesting perspectives in quantum optical communications. Although this ability to squeeze all quadratures seemingly opens a way to instantaneous signaling by circumventing the quantum no-cloning theorem, we explain the subtle mechanism by which such a causality violation is forbidden, even on an heralded basis.

Original languageEnglish (US)
Article number012324
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number1
StatePublished - Jul 20 2012
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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