Single-photon scattering controlled by an imperfect cavity

TL;DR

This paper investigates how an imperfect cavity affects single-photon transport in a coupled-resonator waveguide, revealing non-conservation of probability current and the impact of coupling strength and spectral width on transmission.

Contribution

It introduces a Lorentzian spectrum to model dissipation and analyzes the effects of an imperfect cavity on photon transport, highlighting new phenomena such as probability current non-conservation.

Findings

Probability current conservation can be broken in a Hermitian system.

Transmission decreases with increased coupling strength.

Spectral width significantly suppresses transmission off-resonance.

Abstract

We study the single-photon transport in the coupled-resonator waveguide (CRW) controlled by an imperfect cavity. A Lorentzian spectrum is introduced to describe the dissipation. We find that the probability current conservation can be broken, although the imperfect cavity is a Hermitian system. The coupling strength between the imperfect cavity and the CRW has significant influences near the resonant frequency. With the increase of the coupling strength, the transmission coefficient becomes smaller. The spectral width plays a dominant role under the off-resonant condition, where the transmission coefficient is greatly suppressed with the increase of the spectral width. We also observe an abrupt jump of the transmission and reflection coefficients when the hopping amplitude is large enough. All the distinctive behaviors are closely related to the complex effective potential induced by the imperfect cavity.