Single-photon frequency-comb generation in a one-dimensional waveguide coupled to two atomic arrays

Abstract

An atomic chain coupled to a one-dimensional (1D) photonic waveguide can become a very good atom mirror. This atom mirror can have a very high reflectivity for a single-photon pulse due to the collective interaction between the atoms. Two atom arrays coupled to a 1D waveguide can form a good cavity. When a single-photon pulse is incident from one side of the cavity, only a discrete subset of photon frequencies can transmit the cavity and the transmitted frequencies are almost equally spaced, which is similar to a frequency comb. The linewidth of the comb frequency can be reduced if we increase the atom number in the atomic arrays. More interestingly, if the photon pulse is initially inside the cavity, the photon spectrum after a long time of interaction is also discretized with the comb frequencies being significantly amplified while other frequencies being largely suppressed. This single-photon frequency comb may be useful for precision measurement.