Spontaneous-relaxation-rate suppression in cavities with PT symmetry

Abstract

We compute the spontaneous relaxation rate of a two-level atom in a planar cavity with parity ($\mathcal{P}$) and parity-time ($\mathcal{PT}$) symmetry. We find that at the center of a $\mathcal{PT}$-symmetric cavity the evanescent contribution to the relaxation rate is greatly suppressed. As this is the dominant relaxation pathway for cavities smaller than the transition wavelength, $\mathcal{PT}$-symmetric microcavities are able to suppress the spontaneous relaxation rate dramatically and, in some cases, reduce it to below the free-space level. The ability to reduce the relaxation rate and lengthen the excited-state lifetime has many applications in quantum control and can, for example, be used to increase atomic trapping times, improve photonic storage, and help maintain the coherence of atomic qubits.