Ultralow-Noise Room-Temperature Quantum Memory for Polarization Qubits

Here, we show an ultralow-noise regime of operation in a simple quantum memory in warm 87Rb atomic vapor. By modeling the quantum dynamics of four-level room-temperature atoms, we achieve fidelities > 90% for single-photon-level polarization qubits, surpassing any classical strategies exploiting the nonunitary memory efficiency. Additionally, we show experimental techniques capable of producing fidelities close to unity. Our results demonstrate the potential of simple, resource-moderate experimental room-temperature quantum devices.