压缩态光场在光纤信道传输过程中的量子误差修正

Quantum Error Correction of Squeezed States Transmitted over Optical Fiber Channel

本文提出了四光纤通道量子误差修正方案,利用建立关联噪声通道实现量子态在光纤信道传输时的量子误差修正,完成压缩态光场在光纤信道的有效传输。理论分析了方案中光纤关联噪声通道的关联度、光纤传输距离、本底振荡光的功率等参数对量子误差修正的影响。光纤传输距离和本底振荡光功率越大,引入的额外噪声功率越大。光纤关联噪声通道的关联程度越高,量子误差修正效果越好。当光纤关联噪声通道为理想关联噪声通道时,额外噪声可以被完全去除,压缩态光场的量子特性随着传输距离的增加不会消失。当光纤关联噪声通道只有部分关联时,也可实现压缩态光场在光纤信道传输过程中的量子误差修正。该研究为城域的连续变量光纤量子信息等研究奠定基础。

Fiber channel is the best choice for metropolitan quantum information processing due to its advantages of high compatibility,low cost and not easy to be affected by environment.However,when the non-classical optical field is transmitted in the fiber,it will be affected by the extra noise,leading to decoherence,and thus the quantum properties will be reduced or disappeared.With the development of quantum information in long distance fiber,how to realize the non-classical light field in fiber channel transmission without the influence of extra noise has been paid more and more attention.In this paper,a four-fiber channel quantum error correction scheme is proposed theoretically.The quantum error correction of the quantum state in the fiber channel is realized by establishing the correlated noise channel,and the effective transmission of the squeezed state optical field in the fiber channel is completed.The influence of parameters such as the correlation degree of the optical fiber correlated noise channel,the optical fiber transmission distance and the power of the local oscillating light on the quantum error correction is analyzed theoretically.The numerical simulation of our scheme shows that,when the noise is ideally correlated,the extra noise can be completely removed,and the quantum characteristics of the squeezed state optical field will not disappear with the increase of transmission distance and the power of the local oscillator(LO)beam,so the quantum state is ideally protected.Even if the noise in the established correlation noise channel is only partially correlated,our error correction scheme still effectively reduces the extra noise and enhances the transmission distance of the non-classical optical field in the fiber channel.When the relative phase of the correlated noise is assumed to beπ/2,the transmission distance of the squeezed state light field with a squeezing degree of 10 d B in the fiber channel can be increased from 10 km to 30 km when the power of the LO is 0.2 m W.This study lays a foundation for the research of continuous variable fiber quantum information in metropolitan area.