Number-resolving photon detectors with atoms coupled to waveguides
Daniel Malz, J. I. Cirac · 2019
Number-resolving single-photon detectors represent a key technology for a host of quantum optics protocols, comprising quantum state preparation, quantum metrology, entanglement distribution, and quantum computing. Despite significant advances over the last few decades, state-of-the-art technology can distinguish only very low photon numbers with high fidelity. We show that (artificial) atoms coupled to photonic waveguides constitute an ideal platform to entirely absorb incident photonic wavepackets, even in the presence of disorder and finite Purcell factors, with a fidelity increasing with the number of atoms. Absorption is achieved through engineering a decay channel to a metastable state, such that readout of the atomic state after absorption yields a number-resolving measurement of photon number.