1.5微米波段主动频分复用宣布式单光子源

Single photon sources (SPSs) at 1.5 μm are key ingredients for quantum communication and computation technologies. However, current realization of such SPSs is far from perfect, hence limiting the performance of these applications. In particular, the commonly utilized heralded single photon sources (HSPSs) based on the spontaneous nonlinear optical process are intrinsically probabilistic. Fortunately, active multiplexing has been proposed to overcome this limitation, and, hopefully, can develop active multiplexing HSPS close to an ideal SPS. Here, we propose a novel multiplexing approach in the spectral degree of freedom. Our proposal includes, (1) developing a systematic model to quantify the physical influence of such active multiplexing HSPS, and to summarize the technique principles for improving the performance of such source; (2) based on cascaded nonlinear optical process in periodically poled lithium niobate and optical narrow filtering technique, realize the generation of broadband multi-modes correlated photon pair in spectral; (3) based on high-performance single photon detector and frequency-shifting of single photons, demonstrate the feasibility of active spectral multiplexing HSPS; (4) through measurements of coincidence counting, HBT effect and HOM interference, exam the deterministic property, single-photon purity and indistinguishability of the HSPS, respectively. Based on our project, we will clearly understand an avenue towards high-quality active multiplexing HSPSs, which will be under the right of our intellectual property.

1.5微米波段单光子源是量子通信和量子计算中的重要部件，但此类单光子源的现有方案仍远非完美，大大限制了以上应用的性能。基于自发非线性光学过程的宣布式单光子源，已经取得了广泛地应用，但其性能受限于内禀的随机特性。主动复用方案可突破该限制，实现与理想单光子源性能相比拟的复用宣布式单光子源。本项目拟在光子频域自由度下实现复用宣布式单光子源，内容包括：（1）建立主动复用宣布式单光子源的通用理论模型，定量分析其性能影响因素，总结实现此类单光子源的技术原则；（2）基于单根周期极化铌酸锂波导中的倍频-自发参量下转换和窄带光学滤波，产生频域-多模关联光子对；（3）基于单光子探测和单光子移频，实验论证主动频分复用宣布式单光子源；（4）通过测量符合计数、HBT效应和HOM干涉，分别考察宣布输出光子的确定性、单光子纯度和不可区分性等。通过项目实施，以期明确具有自主知识产权的高性能频分复用宣布式单光子源方案。

1.5微米波段单光子源是量子通信和线性光学量子计算中不可或缺的部件。以自发非线性光学过程为基础的宣布式单光子源是一种重要的单光子源。但是由于其内禀的随机特性，光子源的亮度和单光子纯度存在着此消彼涨的关系，这给其在高性能量子通信和量子计算中的应用带来了显著的困难。为了突破该限制，本项目进行了光通信波段频分复用宣布式单光子源的理论和实验研究，取得了若干实质性的进展。具体的研究内容和进展包括：（1）通过攻克大斜率斜坡电子学脉冲产生问题，结合光学相位调制技术在实验上实现了光通信波段的单光子移频技术；（2）实验上实现了含单光子移频技术的Hong-Ou-Mandel干涉，证实单光子移频技术可以有效擦除双光子的频率可区分性。（3）通过级联的二阶非线性过程，产生了三频道量子关联光子对；（4）实验实现了主动频分复用宣布式单光子源，对其单光子速率、信噪比、二阶关联特性以及其与弱相干单光子源之间的光子不可区分性进行了实验研究。在单光子速率为3.1 kHz时，二阶关联函数值可低至0.0006±0.0001。本项目取得的进展为进一步实现频分复用的量子隐形传态、量子存储等一系列量子纠缠通道研究奠定了基础。