Tunable directional photon scattering from a pair of superconducting qubits

Abstract

The ability to control the direction of scattered light is crucial to provide flexibility and scalability for a wide range of on-chip applications, such as integrated photonics, quantum information processing, and nonlinear optics. Tunable directionality can be achieved by applying external magnetic fields that modify optical selection rules, by using nonlinear effects, or interactions with vibrations. However, these approaches are less suitable to control microwave photon propagation inside integrated superconducting quantum devices. Here, we demonstrate on-demand tunable directional scattering based on two periodically modulated transmon qubits coupled to a transmission line at a fixed distance. By changing the relative phase between the modulation tones, we realize unidirectional forward or backward photon scattering. Such an in-situ switchable mirror represents a versatile tool for intra- and inter-chip microwave photonic processors. In the future, a lattice of qubits can be used to realize topological circuits that exhibit strong nonreciprocity or chirality.

Correlated Two-Photon Scattering in a 1d Waveguide Coupled to a N-Type Four-Level Emitter Guwenju

“…The nonlinearity of atomic system would induce photon-photon correlations, while photon-photon correlations induced tunneling or blocking of photons would affect transmission and reflection of photons [35][36][37][38]. Therefore, a clear understanding of the nature of photon-photon correlations is crucial to figure out how various quantum devices work, such as a switchable mirror [39] or a single-photon router [40]. The fewphoton scattering wavefunctions exhibit a common structure: the two-particle plane wave with momenta of photons rearranged and bound state.…”