Temporal Distinguishability of an N-photon State and Its Characterization by Quantum Interference

摘要

We present a multi-mode model to describe an arbitrary N-photon state. In general, the N photons can be distinguished through their temporal modes. From this model, we can find the criteria for the N photons in an indistinguishable state of a single temporal mode or in different temporal modes. We find that simple multi-photon detection scheme cannot distinguish N photons in different temporal modes and only a multi-photon interference experiment can accomplish the goal. We identified an interference scheme that can quantitatively characterize the temporal distinguishability of an N-photon state. The idea is applied to three-, four-, and six-photon states experimentally.