【摘要】 在87Rb冷原子系综中通过自发拉曼散射过程产生原子自旋波与光子的关联，利用偏振干涉仪将与磁敏感自旋波关联的Stokes光子的两个空间模式编码为一个偏振量子比特，产生磁敏感自旋波与光子的纠缠源。采用近共线装置和精确补偿地磁场，纠缠源的寿命达到900μs,Bell参量S=2.58±0.03。更多还原

【Abstract】 Quantum repeater is important for long-distance quantum communication and scalable quantum network. The basic idea of quantum repeater scheme is to divide the long-distance transmission channel into several shorter sub-channels and extend the entanglement to the whole transmission channel through the entanglement swap between two adjacent sub-channels. DuanLukin-Cirac-Zoller(DLCZ) protocol is a long-distance entanglement distribution scheme that has been widely studied in recent years. The core of DLCZ protocol is the spontaneous Raman scattering process, which produces a photon and an associated spinwave excitation with a certain probability. The entanglement lifetime is one of the key parameters of a quantum entanglement interface in the experiment of atom-photon entanglement. Although storage lifetime based on magnetic field insensitive spinwave atom-photon entanglement has reached the order of milliseconds, there is no report on long-lived atom-photon entanglement source based on magnetic field-sensitive spin-wave till now. Based on the above research background, we place the87Rb cold atomic ensemble in a polarization interferometer formed by a pair of beam displacers, which encode two spatial modes of a photon associated with magnetic field sensitive spin waves generated by spontaneous Raman scattering process into a polarization qubit, realizing a long-lived atom-photon entanglement source based on magnetic field sensitive spin-wave. The storage lifetime of a magnetic field sensitive entanglement source is mainly affected by magnetic field noise and atomic motion. The effect of atomic motion is minimized by increasing the spin-wave wavelength through decreasing the angle between the write-read light and Stokes-anti-Stokes photon detection directions. The influence of magnetic field noise is minimized by accurately compensating for environmental magnetic field by utilizing retrieval efficiency as a reference. The entanglement source lifetime reaches 900 μs, the Bell parameter S = 2.58 ± 0.03, which violates the Bell inequality by 19.3 standard deviations. This work enriched the study of atom-photon quantum interfaces and provided the foundation for the realization of long-distance quantum communication.更多还原