Thermal-difference states of light: Quantum states of heralded photons

摘要: We introduce the thermal-difference states (TDS), a three-parameter family of single-mode non-Gaussian bosonic whose density operator is weighted difference two thermal states. show that "heralded photons" generated via parametric down-conversion (PDC) are precisely those among TDS nonclassical, meaning they have negative P-function. The three parameters correspond in context to initial brightness PDC and transmittances, characterizing linear loss signal idler channels. At low unit heralded photon state known be single-photon state. explore influence on mode. In particular, we analyze nonclassicality by computing several measures nonclassicality, such as volume Wigner function, sum quantum Fisher information for quadratures, ordering sensitivity, introduced recently us [Phys. Rev. Lett. 122, 080402 (2019)]. argue finally provide new benchmark analysis variety properties