Liang Haidong, Gu Tian, Lou Yanchao, Yang Chengyuan, Ma Chaojie, Qi Jiajie, Bettiol Andrew A, Wang Xilin
Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542, Singapore.
State Key Laboratory for Mesoscopic Physics, Frontiers Science Centre for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China.
Sci Adv. 2025 Jan 24;11(4):eadt3710. doi: 10.1126/sciadv.adt3710. Epub 2025 Jan 22.
Entangled photon-pair sources are pivotal in various quantum applications. Miniaturizing the quantum devices to meet the requirement in limited space applications drives the search for ultracompact entangled photon-pair sources. The rise of two-dimensional (2D) semiconductors has been demonstrated as ultracompact entangled photon-pair sources. However, the photon-pair generation rate and purity are relatively low, and the strong photoluminescence in 2D semiconductors also makes the operational wavelength range limited. Here, we use the spontaneous parametric down conversion (SPDC) of rhombohedral boron nitride (rBN) as a polarization entangled photon-pair source. We have achieved a generation rate of more than 120 hertz (a record-high SPDC coincidence rate with 2D materials) and a high-purity photon-pair generation with a coincidence-to-accidental ratio of above 200. Tunable Bell state generation is also demonstrated by simply rotating the pump polarization, with a fidelity up to 0.93. Our results suggest rBN as an ideal candidate for on-chip integrated quantum devices.
纠缠光子对源在各种量子应用中至关重要。将量子设备小型化以满足有限空间应用的需求，推动了对超紧凑型纠缠光子对源的探索。二维（2D）半导体已被证明是超紧凑型纠缠光子对源。然而，光子对产生率和纯度相对较低，并且二维半导体中的强光致发光也使得工作波长范围受限。在此，我们利用菱面体氮化硼（rBN）的自发参量下转换（SPDC）作为偏振纠缠光子对源。我们实现了超过120赫兹的产生率（与二维材料相比创纪录的高SPDC符合率）以及符合与偶然比高于200的高纯度光子对产生。通过简单地旋转泵浦偏振，还展示了可调谐的贝尔态产生，保真度高达0.93。我们的结果表明rBN是片上集成量子设备的理想候选者。
