Generation of Gaussian-Shape Single Photons for High Efficiency Quantum Storage

We report the generation of heralded single photons with Gaussian-shape temporal waveforms through the spatial light modulation technique in an atomic ensemble. Both the full width at half maximum and the peak position of the Gaussian waveform can be controlled while the single photon nature holds well. We also analyze the bandwidth of the generated single photons in frequency domain and show how the sidebands of the frequency spectrum are modified by the shape of the temporal waveform. The generated single photons are especially suited for the realization of high efficiency quantum storage based on electromagnetically induced transparency.     

球面波干涉法测量拉盖尔-高斯光的轨道角动量

采用球面波的拉盖尔-高斯光(LG光)和平面波的基模高斯光干涉的方法 ,可观察到多叶螺旋的干涉图样,螺旋的叶数即是LG光的拓扑荷数,由拓扑荷数可知光子的轨道角动量.利用涡旋相位片产生拓扑荷数1～8的LG光,研究了光强比和偏振条件对干涉图样的影响.为获得高对比度的干涉图样,要求LG光和高斯光的偏振方向相同并且光强基本相等.球面波干涉法用于测量LG光的轨道角动量简单直观,与干涉光强空间分布的细节无关,因此对光强扰动和背景噪声不敏感.     

基于Rydberg原子天线的太赫兹测量

Rydberg原子在微波和太赫兹频段具有极大的电偶极矩,利用量子干涉效应可实现对该频段电磁波场强的高灵敏探测,理论上灵敏度可达到远高于现有探测技术的水平.基于Rydberg原子量子效应的电磁场探测及精密测量技术在太赫兹的场强和功率计量、太赫兹通信和太赫兹成像等方面有着巨大的应用前景.本文回顾了基于Rydberg原子量子干涉效应实现电磁波电场自校准和可溯源测量的基本理论和实验技术,详细介绍了基于Rydberg原子的高灵敏太赫兹场强测量、太赫兹近场高速成像和太赫兹数字通信的基本原理和技术方案.最后简单介绍了本研究团队正在开展的基于Rydberg原子的太赫兹探测工作.