High-gain parametric down-conversion and its applications

Spontaneous parametric down-conversion is a nonlinear process in which higher-energy photons decay in pairs of lower-energy daughter photons, which are then entangled in time/energy, in position/momentum, and sometimes in polarization. When parametric down-conversion is pumped strongly, the number of photon pairs becomes so large that they overlap. The resulting radiation is very bright but still maintains quantum features such as squeezing and photon-number entanglement. In my talk I will speak of its various applications, from efficient generation of optical harmonics and other multiphoton processes [1], to optical coherence tomography with undetected radiation and other examples of nonlinear interferometry [2]. [1] K.Yu. Spasibko et al., Phys. Rev. Lett. 119, 223603 (2017). [2] M. V. Chekhova and Z. Y. Ou, AOP 8, 104 (2016).