渥太华大学Robert W. Boyd团队研究了高增益参量下转换产生的多光子纠缠态空间施密特模的有效表征。该研究于2025年2月27日发表于《物理评论A》杂志。

有效表征光纠缠态空间相关性的能力对于量子成像等许多量子技术的应用至关重要。

研究组展示了高增益参量下转换产生的光的明亮多光子纠缠态的空间施密特模和施密特光谱的高效理论和实验表征。与之前的研究相比，他们利用了信号场的近似准均匀性和各向同性，并大大减少了实验和理论表征过程中涉及的数值计算。在该特定情况下，实验数据集由5000张每张256×256像素的单镜头图像组成，该方法将整体计算时间减少了2个数量级。

对于更大的输入大小，这种加速将更加显著。因此，研究组能够快速表征一系列泵浦振幅的施密特模和施密特谱，并研究其随增益增加的变化。该结果清楚地表明，随着增益的增加，施密特模变宽，施密特谱变窄，理论和实验结果一致。

附：英文原文

Title: Efficient characterization of spatial Schmidt modes of multiphoton entangled states produced from high-gain parametric down-conversion

Author: Mahtab Amooei, Girish Kulkarni, Jeremy Upham, Robert W. Boyd

Issue&Volume: 2025/02/27

Abstract: The ability to efficiently characterize the spatial correlations of entangled states of light is critical for applications of many quantum technologies such as quantum imaging. Here, we demonstrate highly efficient theoretical and experimental characterization of the spatial Schmidt modes and the Schmidt spectrum of bright multiphoton entangled states of light produced from high-gain parametric down-conversion. In contrast to previous studies, we exploit the approximate quasihomogeneity and isotropy of the signal field and dramatically reduce the numerical computations involved in the experimental and theoretical characterization procedures. In our particular case where our experimental datasets consist of 5000 single-shot images of 256×256 pixels each, our method reduced the overall computation time by 2 orders of magnitude. This speedup would be even more dramatic for larger input sizes. Consequently, we are able to rapidly characterize the Schmidt modes and the Schmidt spectrum for a range of pump amplitudes and study their variation with increasing gain. Our results clearly reveal the broadening of the Schmidt modes and the narrowing of the Schmidt spectrum for increasing gain with agreement between theory and experiment.

DOI: 10.1103/PhysRevA.111.023714

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.111.023714