轨道角动量复用光场的高斯量子关联  

Gaussian Quantum Discord of Orbital Angular Momentum Multiplexed Optical Fields

作　　者：马荣[1,2,3] 温虹 曾理 武晓蔚 秦忠忠 苏晓龙 MA Rong;WEN Hong;ZENG Li;WU Xiao-wei;QIN Zhong-zhong;SU Xiao-long(State Key Laboratory of Quantum Optics and Quantum Optics Devices,Institute of Opto-Electronics,Shanxi University,Taiyuan 030006,China;Collaborative Innovation Center of Extreme Optics,Shanxi University,Taiyuan 030006,China;School of Physical and Electronic Engineering,Shanxi University,Taiyuan 030006,China)

机构地区：[1]山西大学光电研究所,量子光学与光量子器件国家重点实验室,山西太原030006 [2]山西大学,极端光学协同创新中心,山西太原030006 [3]山西大学,物理电子工程学院,山西太原030006

出　　处：《量子光学学报》2022年第2期123-130,共8页Journal of Quantum Optics

基　　金：国家自然科学基金(11974227,11834010,61905135);山西省基础研究计划(20210302122002);山西省回国留学人员科研资助项目(2021-003);山西省“1331工程”重点学科建设计划。

摘　　要：连续变量纠缠态光场是实现量子计算、量子通信和量子精密测量的重要量子资源。轨道角动量复用是增加量子通信信道容量的一种有效方式。我们利用铯原子系综中的四波混频过程制备了轨道角动量复用的连续变量纠缠态光场,并实验证明携带l=1,2阶轨道角动量的EPR纠缠态光场可以获得与l=0模式的EPR纠缠态光场相同的纠缠度。此外,我们采用高斯量子失谐表征了携带l=0,1,2阶轨道角动量光场的量子关联,并研究了其在损耗信道中的演化。结果表明轨道角动量复用光场的高斯量子关联在损耗环境中具有鲁棒性。研究结果为利用轨道角动量复用的连续变量纠缠态光场实现高信道容量量子通信提供了参考。Continuous-variable entangled optical fields are important quantum resources for realizing quantum computing, quantum communication and quantum precision measurement. Continuous-variable quantum systems have the advantages of deterministic generation, high-efficiency quantum detection, and excellent compatibility with classical communication systems. Quantum channel capacity is an important figure of merit in quantum communication. Multiplexing is useful in improving the quantum channel capacity, which is realized by combining multiple discrete values of a certain degree of freedom into a single channel, such as wavelength, polarization, and temporal mode. Orbital angular momentum multiplexing is an efficient way to increase the channel capacity in quantum communication, since in principle the topological charge of orbital angular momentum can be arbitrary integers. Four-wave mixing process based on the double-Λ energy level structure of alkali metal atomic ensemble is an efficient way to prepare a spatially multi-mode entangled state with the advantages of naturally matching the atomic transition. It has been widely used in quantum state engineering, quantum precision measurement, quantum beam splitter, and so on. Recently, our group generates orbital angular momentum multiplexed continuous variable entangled state based on the four-wave mixing process in cesium atomic ensemble, and realized deterministic distribution of orbital angular momentum multiplexed quantum entanglement and quantum steering. In this paper, we experimentally demonstrate that the entanglement of EPR entangled state carrying l = 1, 2order topological charge is the same as that of l = 0 order Gaussian mode. Furthermore, we characterize quantum correlation of optical fields carrying l = 0, 1, 2 order orbital angular momentum in terms of Gaussian quantum discord and investigate its evolution in a lossy quantum channel. Our results show that Gaussian quantum correlation of orbital angular momentum multiplexed optical fields is robust in a loss

关 键 词：轨道角动量复用 连续变量纠缠 量子失谐 四波混频 

分 类 号：O436[机械工程—光学工程]