Atomic-type photonic crystals with adjustable band gaps

If the electromagnetic waves are scattered by the periodic structure of media with different refractive indexes, a band gap in the transmitted spectrum can be generated. This is the photonic crystal whose band gap is usually uncontrollable as its structure parameters are fixed after the fabrication. Alternatively, based on the quantum theory in real space for single photons transporting along a one-dimensional waveguide embed by a series of two-level atoms, we propose here a quantum mechanical configuration to implement the photonic crystal with adjustable band gap. It is shown that if the scattering two-level atoms are arranged as a periodic array, the desirable band gap in the photonic transmission spectrum can be formed. This is the atomic-type photonic crystal, in which the center frequency of the gap can be controlled by adjusting the eigenfrequencies of the atoms. The possible physical implementations of our proposal with the voltage-biased superconducting qubits for the centimeter waves and the voltage-biased electrons on liquid helium for the millimeter waves are also discussed. (C) 2021 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement