Waveguide quantum electrodynamics is an emerging field of quantum optics studying interaction of photons propagating in a waveguide with localized quantum emitters. Depending on the platform, the quantum emitters can be realized as semiconductor quantum dots, quantum solid-state defects, cold atoms, or superconducting qubits. Such systems are promising for quantum information processing, quantum memory applications, generation and detection of quantum light.
Light-coupled arrays of emitters form an inherently open system due to the possibility of spontaneous photon emission into the far field. Interestingly, the decay rate of collective eigenmodes within these emitter arrays can be either enhanced (for superradiant modes) or suppressed (for subradiant modes) when compared to the decay rate of an individual emitter. The development of such collective modes can be described by effective non-Hermitian Hamiltonians, known for their unique properties.
Quantum emitter arrays, in which the emitter resonance frequencies are not fixed but are dynamically modulated, provide exciting new avenues for controlling both the direction and the quantum correlations of emitted photons.