Photon statistics of one- and two-photon subtracted states at telecom wavelength reconstructed via direct detection

Photon-number-resolving superconducting photon detectors promise to simplify detection schemes where only photon statistics matters in the few-photon regimes. Employed in one- and two-photon subtraction protocols, they allowed reconstruction of the photon number distribution for coherent and thermal states obtained from a pulsed laser at telecom wavelengths. The experimental setup is based on photon detection events recorded using a photon-number-resolving detector based on an array of eight superconducting NbN nanostrips working at 2.2 K. Photon subtraction was implemented using a low-reflectivity beam splitter and two superconducting nanostrip single photon detectors with an efficiency higher than 90% and a dark count rate of 1 cps. Our results confirm that our scheme accurately reproduces the theoretically expected effects of the annihilation operator on the states, achieving a fidelity higher than 99%.