Fiber-coupled broadband quantum memory for polarization-encoded photonic qubits

Abstract: Various near-term quantum networking applications will benefit from low-loss, fiber-coupled photonic quantum memory devices with high efficiencies. We demonstrate a fiber-coupled loop-and-switch quantum memory platform with a pass-through efficiency of ~54% and an overall storage efficiency that scales as ~0.5^N+1 where N is the number of storage cycles. We highlight the trade-off between memory lifetime and qubit accessibility in this platform by using two different storage cycle times of ~40 nanoseconds and ~0.5 microseconds, and demonstrate high-fidelity storage and retrieval of ultra-broadband single-photon polarization qubits in both cases.