Error-Detected State Transfer and Entanglement in a Superconducting Quantum Network
Luke Burkhart, James D. Teoh, Yaxing Zhang, Christopher Axline, Luigi Frunzio, Michel Devoret, Liang Jiang, S. M. Girvin, Robert Schoelkopf
Abstract
Microwave photons are used to wire up modular quantum processors, but mitigating the effects of loss between modules remains a crucial challenge. We use a low-loss bus resonator to couple bosonic qubits across a superconducting network with protocols made robust to photon loss in the bus. We transfer a multiphoton qubit and track loss events, improving the fidelity to the break-even point with respect to the best uncorrectable encoding. We also demonstrate a entanglement protocol using Hong-Ou-Mandel interference and error detection to prepare a two-photon Bell state with fidelity 94% and success probability 0.79, halving the error obtained with a single photon. This network link also presents new opportunities for resource-efficient direct gates between modules.