Deterministic Bidirectional Communication and Remote Entanglement Generation Between Superconducting Quantum Processors

We propose and experimentally demonstrate a simple and efficient scheme for photonic communication between two remote superconducting modules. Each module consists of a random access quantum information processor with eight-qubit multimode memory and a single flux tunable transmon. The two processor chips are connected through a one-meter long coaxial cable that is coupled to a dedicated "communication" resonator on each chip. The two communication resonators hybridize with a mode of the cable to form a dark "communication mode" that is highly immune to decay in the coaxial cable. We modulate the transmon frequency via a parametric drive to generate sideband interactions between the transmon and the communication mode. We demonstrate bidirectional single-photon transfer with a success probability exceeding 60 %, and generate an entangled Bell pair with a fidelity of 79.3 $\pm$ 0.3 %.