Chiral Cavity QED in a Synthetic Gauge Field

We share results from a recent manuscript (arXiv:2109.06033) in which we demonstrate strong coupling between a superconducting transmon qubit and a square lattice of 3D microwave resonators engineered to host a synthetic magnetic field for photons. This quantum nonlinear metamaterial hosts spectrally distinct, topologically protected edge channels and is the first photonic topological lattice platform compatible with strong interactions. We explore cavity quantum electrodynamics in this chiral system: we count and manipulate individual photons in each lattice mode, driving resonant interactions between the nonlinear emitter and individually addressable modes of the topological lattice vacuum, and observe the Lamb shift on the qubit from the synthetic vacuum of the lattice. We share progress towards measurements with multiple nonlinearities coupled to this photonic lattice, enabling communication via the chiral lattice edge channels and opening avenues towards exploring photon-photon interactions and many-body physics in this synthetic quantum material.