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We show a scheme to distribute the entanglement by using three-mode separable Gaussian state prepared with imperfect equipments.The scheme achieves the aim that the entanglement is distributed between two distant parties with only Gaussian operations and linear optics elements.Moreover,we analyse the logarithmic negativity of the entanglement shared between the two parties when the systems are imperfect and arrive at the conclusion that the logarithmic negativity is asymptotically stable with fluctuations within a certain space range. 相似文献
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2013年9月6日,美国宇航局(NASA)发射了月球大气与尘埃环境探测器(LADEE)飞船。针对LADEE上进行的月球激光通信演示验证(LLCD),从终端设计方面进行综述。LLCD系统主要包括一个安装在LADEE上的太空终端、三个地面终端以及一个协调该演示验证的地面运行中心,其中太空终端主要与一个多孔径望远镜阵列地面终端完成最高数据率为622 Mb/s的下行链路以及最高数据率为20 Mb/s的上行链路。考虑到该地面终端所在地的天气因素,又选择了两个备用地面终端,用来提供地理多样性,支持该演示验证。 相似文献
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The security of quantum secret sharing based on entanglement
swapping is revisited and a participant attack is presented. In this
attack two dishonest agents together can illegally recover the
secret quantum state without the help of any other controller, and
it will not be detected by any other users. Furthermore, by
modifying the distribution process of particles and adding a
detection step after each distribution process, we propose an
improved protocol which can resist this kind of attack. 相似文献
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研究对象是偏移正交幅度调制的相干光正交频分复用通信(CO-OFDM-OQAM)系统的信道估计方法。为了减少训练序列所占用的频谱资源,进一步提升频谱效率,为偏振复用CO-OFDM-OQAM系统提出了一种新的频域信道估计方法。该方法利用偏振复用系统的解调原理和固有虚部干扰系数的对称性规律设计全负载型实值导频方案,结合插值法,将每个偏振态上训练序列需要占用的频域符号个数降低为4。此外,该方法的另一个优势是具有更好的功率峰均比。搭建了偏振复用CO-OFDM-OQAM系统的数值仿真平台,在背靠背(BtB)、100 km和200 km光纤传输3种场景下对所提方法的频谱效率、功率峰均比和信道估计性能进行了验证。获得的结果证实所提方法能够提高频谱效率,而且功率峰均比更加优良。 相似文献