Abstract

Photonic entanglement distribution with wavelength division multiplexing (WDM) technology is a promising method for increasing capacity in quantum communication. So far, various experiments [1,2] have been actively conducted by using broadband entangled photon pairs based on spontaneous parametric down-conversion (SPDC) with WDM-compatible spectral filters. However, the separation of broadband photon pairs over the channels inevitably wastes a large amount of photon energy for sufficient suppression of channel crosstalk, which causes photon pairs to have a low brightness. The cavity-enhanced SPDC can be used to overcome this problem. Because the generated photon pairs are gathered into resonant peaks with a spectral spacing determined by the cavity, the joint spectrum of the photon pairs becomes a comb-like structure called a biphoton frequency comb [6].

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