Fig. 4: NPQD applications.
a, Entanglement generation between an atom–photon entanglement source and a heralded quantum memory (HQM). An NPQD along the transmission channel can speed up the mean sender–receiver entanglement time compared to the standard situation. The blue and green coloured lines represent the entanglement speed-up and the NPQD entanglement time, respectively. b, Photonic qubits are remotely sent to a receiver for a follow-up operation that involves precious resources (for example, long-distance entanglement). The qubit amplification gives the ratio of the probability of having a photon after its nondestructive detection at the NPQD to the probability of having a photon before detection (Piq). c, Photonic qubits transfer to a noisy qubit measurement set-up (QMS). Gating the QMS with the NPQD herald signal improves the SNR. d, Bell test based on precertification of the photon’s presence6. The dashed lines in the plots represent the situation of a perfect NPQD (a, c) or a dark-count-free NPQD (b).
