Generating Multimode Entangled Microwaves with a Superconducting Parametric Cavity

The generation and distribution of entanglement is a central topic in quantum information science, enabling important applications in quantum communication and computing. This has created great interest in creating ``flying'' entangled states. The authors present a parametric cavity that generates multimode states of microwave photons with programmable entanglement structure. This advance will facilitate progress in a range of fields, including microwave cluster states, error-correctable logical qubits for quantum communication, and the quantum simulation of relativistic quantum information processing systems.