Fletcher Alasdair I, Pirandola Stefano
Department of Computer Science, University of York, York, YO10 5GH, UK.
Sci Rep. 2022 Oct 15;12(1):17329. doi: 10.1038/s41598-022-22251-8.
A continuous variable (CV), measurement device independent (MDI) quantum key distribution (QKD) protocol is analyzed, enabling three parties to connect for quantum conferencing. We utilise a generalised Bell detection at an untrusted relay and a postselection procedure, in which distant parties reconcile on the signs of the displacements of the quadratures of their prepared coherent states. We derive the rate of the protocol under a collective pure-loss attack, demonstrating improved rate-distance performance compared to the equivalent non-post-selected protocol. In the symmetric configuration in which all the parties lie the same distance from the relay, we find a positive key rate over 6 km. Such postselection techniques can be used to improve the rate of multi-party quantum conferencing protocols at longer distances at the cost of reduced performance at shorter distances.
分析了一种连续变量（CV）、测量设备无关（MDI）量子密钥分发（QKD）协议，该协议能使三方连接进行量子会议。我们在不可信中继处采用广义贝尔检测和后选择程序，其中远程各方就其制备的相干态正交分量位移的符号进行协调。我们推导了该协议在集体纯损耗攻击下的速率，表明与等效的非后选择协议相比，速率-距离性能有所提高。在所有各方与中继距离相同的对称配置中，我们发现超过6公里有正的密钥率。这种后选择技术可用于提高多方量子会议协议在更长距离的速率，但代价是在较短距离性能降低。
