Thermal-difference states of light: true states of heralded photons
Univ. Lille, CNRS, UMR 8523 -PhLAM -Physique des Lasers Atomes et Molécules, F-59000 Lille, France
2 B. I. Stepanov Institute of Physics, NASB, Nezavisimosti Ave. 68, Minsk 220072 Belarus
3 Univ. Lille, CNRS, UMR 8524 -Laboratoire Paul Painlevé, F-59000 Lille, France
* e-mail: Dmitri.Horoshko@univ-lille.fr
Published online: 15 January 2019
We introduce a three-parameter family of single-mode optical states whose density operator is a weighted difference of two thermal states, the thermal-difference states. We identify the parameter values for which these states have a negative non-singular P-function, implying they are nonclassical. We show that the states of the “heralded photons” generated via spontaneous parametric downconversion belong to this family, with the three parameters corresponding to the nonlinear gain and the losses in the signal and the idler channels. The thermal-difference states yield new benchmark states for the analysis of nonclassicality and quantum macroscopicity criteria.
© The Authors, published by EDP Sciences, 2019
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