Tunable quantum gate between a superconducting atom and a propagating microwave photon

Understand

We propose a two-qubit quantum logic gate between a superconducting atom and a propagating microwave photon.

• The atomic qubit is encoded on its lowest two levels and the photonic qubit is encoded on its carrier frequencies.
• The gate operation completes deterministically upon reflection of a photon, and various two-qubit gates (SWAP, $\sqrt{\rm SWAP}$, and Identity) are realized through {\it in situ} control of the drive field.
• The proposed gate is applicable to construction of a network of superconducting atoms, which enables gate operations between non-neighboring atoms.