近日，陕西科技大学的李百宏及其研究小组与中国科学院国家授时中心的张首刚等人合作并取得一项新进展。经过不懈努力，他们实现双光子在广义量子干涉仪上的全面表征。相关研究成果已于2024年4月2日在国际知名学术期刊《物理评论A》上发表。

该研究团队提出了一种理论方法，该方法通过在组合干涉仪的一个臂中引入频率移位，实现了双光子的完全层析成像。这种方法被命名为广义组合干涉仪，它能够在单个干涉仪中全面重建与频率和及频率差相关的复杂联合频谱振幅。

相比之下，传统的广义Hong-Ou-Mandel和N00N状态干涉仪只能实现双光子的部分层析成像，要么针对频率差，要么针对频率和。因此，这一新方法为具有交换对称性的任意双光子态的全面表征提供了一种替代方法，并在高维量子信息处理领域展现出巨大的应用潜力。

据悉，时频自由度的纠缠光子(双光子)在基础物理和先进量子技术中，都起着至关重要的作用。充分描述它们的特征是一项关键的科学挑战。

附：英文原文

Title: Full characterization of biphotons with a generalized quantum interferometer

Author: Baihong Li, Changhua Chen, Boxin Yuan, Xiaofei Zhang, Ruifang Dong, Shougang Zhang, Rui-Bo Jin

Issue&Volume: 2024/04/02

Abstract: Entangled photons (biphotons) in the time-frequency degree of freedom play a crucial role in both foundational physics and advanced quantum technologies. Fully characterizing them poses a key scientific challenge. Here, we propose a theoretical approach to achieving the complete tomography of biphotons by introducing a frequency shift in one arm of the combination interferometer. Our method, a generalized combination interferometer, enables the reconstruction of the full complex joint spectral amplitude associated with both frequency sum and difference in a single interferometer. In contrast, the generalized Hong-Ou-Mandel and N00N state interferometers only allow for the partial tomography of biphotons, either in frequency difference or frequency sum. This provides an alternative method for full characterization of an arbitrary two-photon state with exchange symmetry and holds potential for applications in high-dimensional quantum information processing.

DOI: 10.1103/PhysRevA.109.043703

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.04370