(Top) Optical micrograph of the device used by Wang et al.  to entangle spatially separated photons stored in superconducting resonators. A and B label the waveguide resonators, which are entangled in the experiment. The phase qubits q0 and q1 are Josephson junction phase qubits, while C is a coupling resonator used to mediate the interaction between the qubits. (Bottom) Equivalent circuit schematic for the device.