Guo Xueshi, Li Xiaoying, Liu Nannan, Ou Z Y
College of Precision Instrument and Opto-electronics Engineering, Tianjin University, Key Laboratory of Optoelectronics Information Technology, Ministry of Education, Tianjin, 300072, P. R. China.
Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA.
Sci Rep. 2016 Jul 26;6:30214. doi: 10.1038/srep30214.
One of the important functions in a communication network is the distribution of information. It is not a problem to accomplish this in a classical system since classical information can be copied at will. However, challenges arise in quantum system because extra quantum noise is often added when the information content of a quantum state is distributed to various users. Here, we experimentally demonstrate a quantum information tap by using a fiber optical parametric amplifier (FOPA) with correlated inputs, whose noise is reduced by the destructive quantum interference through quantum entanglement between the signal and the idler input fields. By measuring the noise figure of the FOPA and comparing with a regular FOPA, we observe an improvement of 0.7 ± 0.1 dB and 0.84 ± 0.09 dB from the signal and idler outputs, respectively. When the low noise FOPA functions as an information splitter, the device has a total information transfer coefficient of Ts+Ti = 1.5 ± 0.2, which is greater than the classical limit of 1. Moreover, this fiber based device works at the 1550 nm telecom band, so it is compatible with the current fiber-optical network for quantum information distribution.
通信网络中的一项重要功能是信息分发。在经典系统中完成此操作并非难题，因为经典信息可以随意复制。然而，在量子系统中会出现挑战，因为当量子态的信息内容分发给不同用户时，通常会添加额外的量子噪声。在此，我们通过使用具有相关输入的光纤光学参量放大器（FOPA）进行实验演示了一种量子信息分路器，其噪声通过信号与闲频输入场之间的量子纠缠产生的相消量子干涉而降低。通过测量FOPA的噪声系数并与常规FOPA进行比较，我们分别观察到信号输出和闲频输出的改善为0.7±0.1 dB和0.84±0.09 dB。当低噪声FOPA用作信息分离器时，该器件的总信息传输系数为Ts+Ti = 1.5±0.2，大于经典极限1。此外，这种基于光纤的器件工作在1550 nm电信波段，因此它与当前用于量子信息分发的光纤网络兼容。
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