Cavity-enhanced and temporally multiplexed atom-photon entanglement interface

• Published in: Optics express Vol. 31; no. 5; p. 7200
• Main Authors: Liu, Hailong, Wang, Minjie, Jiao, Haole, Lu, Jiajin, Fan, Wenxin, Li, Shujing, Wang, Hai
• Format: Journal Article
• Language: English
• Published: United States 27.02.2023
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.483444

Practical realization of quantum repeaters requires quantum memories with high retrieval efficiency, multi-mode storage capacities, and long lifetimes. Here, we report a high-retrieval-efficiency and temporally multiplexed atom-photon entanglement source. A train of 12 write pulses in time is applied to a cold atomic ensemble along different directions, which generates temporally multiplexed pairs of Stokes photons and spin waves via Duan-Lukin-Cirac-Zoller processes. The two arms of a polarization interferometer are used to encode photonic qubits of 12 Stokes temporal modes. The multiplexed spin-wave qubits, each of which is entangled with one Stokes qubit, are stored in a “clock” coherence. A ring cavity that resonates simultaneously with the two arms of the interferometer is used to enhance retrieval from the spin-wave qubits, with the intrinsic retrieval efficiency reaching 70.4%. The multiplexed source gives rise to a ∼12.1-fold increase in atom-photon entanglement-generation probability compared to the single-mode source. The measured Bell parameter for the multiplexed atom-photon entanglement is 2.21(2), along with a memory lifetime of up to ∼125 µs.