Topology-Enhanced Nonreciprocal Scattering and Photon Absorption in a Waveguide

Abstract

Waveguide quantum electrodynamics with multiple atoms provides an important way to study photon transport. In this work, we study the photon transport in a one-dimensional waveguide coupled to a topological atom array. The interaction between light and topology-dressed atoms yields a rich variety of photon scattering phenomena. We find that the nonreciprocal photon reflection originates from the quantum interference of photons scattered by the dissipative edge and bulk modes in the topological atom array. The largest nonreciprocity is found at the magic atomic spacing d = 3λ0/4, where λ0 is the characteristic wavelength of the waveguide. For an odd number of atoms with an extremely small free space decay, the broken inversion and time-reversal symmetries induce a giant anomalous photon loss from the waveguide to free space. Our model can be implemented in superconducting quantum circuits. This work opens a new avenue to manipulate photons via the interaction between light and topological quantum matter.

Dissipative Topological Phase Transition with Strong System-Environment Coupling

“…However, the edge state at d = 3λ 0 /4 has a decay rate that decreases in the non-topological phase and that stops decaying at J 0 = γ 0 /4. In finite systems, the weak emitter-environment coupling, i.e., large J 0 /γ 0 , introduces dissipation of the edge state [55], which is responsible for the enhanced photon absorption [71]. However, the edge state for strong coupling is protected against decoherence in the topological phase.…”