Tunable single-photon diode by chiral quantum physics

TL;DR

This paper demonstrates a chiral quantum physics-based single-photon diode that allows unidirectional photon transmission, with tunable parameters for different emitter types, advancing quantum optical control.

Contribution

It introduces a novel single-photon diode utilizing chiral coupling in waveguides, enabling tunable unidirectional photon transport with practical control mechanisms.

Findings

Perfect diode behavior in ideal chiral coupling with zero transmission in one direction.

Adjustable diode operation for different emitter types and photon frequencies.

Potential for realizing a single-photon switch with high control and efficiency.

Abstract

We investigate the single photon scattering by an emitter chirally coupled to a one-dimensional waveguide. The single-photon transport property is essentially different from the symmetrical coupling case. The single photons propagating towards the emitter in opposite directions show different transmission behaviors, which is a manifestation of the single-photon diode. In the ideal chiral coupling case, the transmission probability of the single photon transport in one direction is zero by critical coupling, while in the opposite direction it is unity. The diode works well only when the single-photon frequency meets certain conditions. For a two-level emitter, the diode works well when the single photon is nearly resonant to the emitter. For a $\Lambda $-type three-level emitter, when the single-photon frequency is greatly altered, we can adjust the parameters of the external laser to ensure the diode works well. The latter provides a manner to realize a single-photon switch, in which the single-photon transmission probability can reach zero or unity although the emitter's decay is considered.