Statistics Of Narrow-band Single Photons For Quantum Memories Generated By Ultrabright Cavity-enhanced Parametric Down-conversion

摘要

Narrow-band single photons represent an important resource for quantum memories due to their efficient interaction with atomic resonances. In this Letter, we report on the generation of photons with 3 MHz linewidth by cavity-enhanced parametric down-conversion and demonstrate direct proof of their single-photon character by detection of heralding idler photons. Compared to a Poissonian source, a suppression of higher-order photon numbers by nearly 2 orders of magnitude could be achieved. Moreover, the brightness of our source exceeds previous realizations by more than a factor of 100.