Multiatomic mirror for perfect reflection of single photons in a wide band of frequency

A resonant two-level atom doped in a one-dimensional waveguide behaves as a mirror, but this single-atom ``mirror'' can only reflect single photons perfectly at a specific frequency. For a one-dimensional coupled-resonator waveguide, we propose to extend the perfect-reflection region from a specific frequency point to a wide band by placing many atoms individually in the resonators in a finite coordinate region of the waveguide. Such a doped resonator array promises to control the propagation of a practical photon wave packet with a certain momentum distribution instead of a single photon, which is ideally represented by a plane wave with a specific momentum. The studies based on the discrete-coordinate scattering theory indicate that such a hybrid structure with finite atoms indeed provides a near-perfect reflection for a single photon in a wide band. We also calculated the photon group velocity distribution, which shows that the perfect-reflection wide band exactly corresponds to the stopping light region.