Few photon transport in a waveguide coupled to a pair of collocated two-level atoms

TL;DR

This paper analyzes how two collocated two-level atoms coupled to a waveguide affect photon transport, revealing quantum interference effects, narrow fluorescence features, and tunable photon statistics in a few-photon regime.

Contribution

It provides exact calculations of scattering matrices for two non-identical atoms and uncovers mechanisms for controlling fluorescence and photon correlations.

Findings

Background fluorescence can be completely quenched by quantum interference.

Narrow fluorescence features emerge when atomic detuning is small.

The system can produce tunable photon bunching and anti-bunching effects.

Abstract

We calculate the one- and two-photon scattering matrices of a pair of collocated non-identical two-level atoms coupled to a waveguide. We show that by proper choice of a two-photon input, the background fluorescence by the atoms may be completely quenched, as a result of quantum interference, and that when the atoms' detuning is smaller than their linewidths, extremely narrow fluorescence features emerge. Furthermore, the system emits a two-photon bound state which can display spatial oscillations/quantum beats, and can be tuned from bunched to anti-bunched statistics as the total photon energy is varied.