Photon shell game in three-resonator circuit quantum electrodynamics

The generation and control of quantum states of light constitute fundamental tasks in cavity quantum electrodynamics(1-10) (QED). The superconducting realization of cavity QED, circuit QED (refs 11-14), enables on-chip microwave photonics, where superconducting qubits(15-18) control and measure individual photon states(19-26). A long-standing issue in cavity QED is the coherent transfer of photons between two or more resonators. Here, we use circuit QED to implement a three-resonator architecture on a single chip, where the resonators are interconnected by two superconducting phase qubits. We use this circuit to shuffle one- and two-photon Fock states between the three resonators, and demonstrate qubit-mediated vacuum Rabi swaps between two resonators. By shuffling superposition states we are also able to demonstrate the high-fidelity phase coherence of the transfer. Our results illustrate the potential for using multi-resonator circuits as photon quantum registers and for creating multipartite entanglement between delocalized bosonic modes(27).