Non-classical correlation between a single photon and the collective spin excited state of a cold atomic ensemble

陆小松, 陈群峰, 史保森 +1 more

Xiaosong Lu, Qunfeng Chen, Bao-Sen Shi +1 more

We experimentally establish a non-classical correlation between a single Stokes photon and the collective spin excited state of a cold atomic ensemble by using a spontaneous Raman scattering process.The correlation between them can be proved by transferring the spin excited state of the atomic ensemble into an anti-Stokes photon and checking the Cauchy-Schwarz inequality between the Stokes and the anti-Stokes photons.The non-classical correlation can be kept for at least 300 ns.

原浩翔 YUAN Hao-xiang, 葛伟 GE Wei, 田龙 Tian Long +3 more

Félix Hoffet, Alexey Vylegzhanin, Emanuele Distante +3 more

A promising platform for quantum information research relies on cavity coupled atomic spin-waves, enabling efficient operations such as quantum memories, quantum light generation and entanglement distribution. In this work, we study the strong coupling between non-classical collective spin excitations generated by Raman scattering in a cold $^{87}\mathrm{Rb}$ atomic ensemble, and a single cavity mode. We report on an intracavity spin wave to single photon conversion efficiency of up to $χ=0.75 \pm 0.02$ in the quantum domain, as evidenced by a violation of the Cauchy-Schwarz inequality. Our work establishes a relationship between the retrieval of an atomic spin wave in the non-classical regime and the vacuum-Rabi splitting. We show that this relationship emerges within the efficiency spectrum, and we finally provide the optimal operational conditions to achieve the maximum intrinsic retrieval efficiency. Our data is well reproduced by simulations based on optical Bloch equations. This work deepens the understanding of cavity-enhanced spin wave readout and its potential applications.

Andrew R. Ferdinand, Alejandro Manjavacas, F. E. Becerra

LI YIFAN