Multimode photonic quantum memory could enhance the information processing speed in a quantum repeater-based quantum network. A large obstacle that impedes the storage of the spatial multimode in a hot atomic ensemble is atomic diffusion, which severely disturbs the structure of the retrieved light field. In this paper, we demonstrate that the elegant Ince-Gaussian (eIG) mode possesses the ability to resist such diffusion. Our experimental results show that the overall structure of the eIG modes under different parameters maintains well after microseconds of storage. In contrast, the standard IG modes under the same circumstance are disrupted and become unrecognizable. Our findings could promote the construction of quantum networks based on room-temperature atoms.

传统光学成像系统主要依靠阵列探测器对目标的空间分布进行探测来达到成像的目的。而单像素成像不需要阵列探测器，在探测端只需要使用一个单点探测器来记录光场的信号，然后利用关联算法来重构目标物体的图像信息。由于单点探测器的技术较为成熟，且成本较为低廉，因此这种成像方式在近些年得到了研究人员的广泛关注，期望单像素成像技术能够应用在X射线、红外、太赫兹等波段。另外，单像素成像技术在生物荧光成像、多光谱成像、三维成像、光场复振幅成像等应用领域也得到了深入的研究。其中光场波前的相位探测在天文观测、医学诊断、光学测量等领域至关重要，研究人员针对这一问题提出了多种基于单像素成像技术进行复振幅成像的方法，这些研究有效地拓展了单像素成像技术的实际应用场景。文中主要介绍了单像素成像技术的历史发展及其基本工作原理，并着重介绍了单像素成像技术在复振幅成像应用中的工作。

A new architecture, naked-eye ghost imaging via photoelectric feedback, is developed that avoids computer algorithm processing. Instead, the proposed scheme uses a photoelectric feedback loop to first realize the correlation (multiplication) process of the traditional ghost imaging system. Then, the vision persistence effect of the naked eye is exploited to implement the integral process and to generate negative images. Two kinds of feedback circuits, the digital circuit and the analog circuit, are presented that can achieve a feedback operation. Based on this design, high-contrast real-time imaging of moving objects is obtained via a special pattern-scanning architecture on a low-speed light-modulation mask.

本文从理论上研究了在双色频率梳激光场驱动下多光子谐波辐射光谱中的相位突变现象。我们利用Floquet理论非微扰地模拟了频率梳激光场与原子分子等量子系统的相互作用过程。谐波辐射信号是多光子偶极跃迁相干叠加的结果，通过调节频率梳激光场间的相对相位，可以相干地控制谐波辐射信号的强度。通过对谐波信号进行傅里叶变换，可以提取不同跃迁路径的相对相位信息。我们通过改变频率梳组激光场的强度和频率组分实现多光子跃迁频率，让其跨越共振跃迁频率时，谐波相位会发生突变。从而可以观测超强激光场驱动下量子系统共振跃迁频率的斯塔克能移。

We demonstrate the generation of non-classical photon pairs in a warm Rb87 atomic vapor cell with no buffer gas or polarization preserving coatings via spontaneous four-wave mixing. We obtain the photon pairs with a 1/e correlation time of 40 ns and the violation of Cauchy–Schwartz inequality by a factor of 23±3. This provides a convenient and efficient method to generate photon pair sources based on an atomic ensemble.

The spin Hall effect of light (SHEL) can be observed by the dark strip resulting from weak measurement. We find that the SHEL of a partially coherent beam (PCB) has a similar phenomenon as well. However, the dark strip in the SHEL of a PCB cannot be explained by considering the beam as an assemblance of coherent speckles. Also, the dark strip in a PCB is not purely dark. By analyzing the autocorrelation, we show that the SHEL of a PCB is the result of overlapping coherent speckles’ SHEL. We further prove our conclusion by adjusting convergence and incident angles. Finally, we develop a qualitative theory to clarify the SHEL of a PCB.