How to improve the routings of single photons using collective atomic effects in chiral waveguide QED (quantum electrodynamics) ladders?

Single-photon routing plays an important role in quantum networking and quantum communication protocols. In the last five years or so it has been shown that perfect single photons routing can be achieved in the single-atom waveguide QED ladders by using chiral light-matter interactions if spontaneous emission is completely suppressed. However, the inclusion of spontaneous emission drastically reduces the routing efficiency. In this talk, we discuss how collective effects arising due to infinitely long-ranged dipole-dipole interactions (DDI) between quantum emitters can protect the routing from spontaneous emission loss. As an example, we consider a one-dimensional dissipative chain of 30 quantum dots coupled with a chiral nanowire. We show that for the experimentally achievable parameters in this setup the routing efficiency can be enhanced from 58% to 95% under the condition of strong DDI [1].

[1] Bibandhan Poudyal and Imran M. Mirza, Collective photon routing improvement in a dissipative quantum emitter chain strongly coupled to a chiral waveguide QED ladder, Phys. Rev. Research, 2(4), 043048 (2020).