A multiple access channel (MAC) consists of multiple senders simultaneously transmitting their messages to a single receiver. For the classical-quantum case (cq-MAC), achievable rates are known assuming that all the messages are decoded, a common assumption in quantum network design. However, such a conventional design approach ignores the global network structure, i.e., the network topology. When a cq-MAC is given as a part of quantum network communication, this work shows that computation properties can be used to boost communication speeds with code design dependently on the network topology. We quantify achievable quantum communication rates of codes with computation property for a two-sender cq-MAC. When the two-sender cq-MAC is a boson coherent channel with binary discrete modulation, we show that it achieves the maximum possible communication rate (the single-user capacity), which cannot be achieved with conventional design. Further, such a rate can be achieved by different detection methods: quantum (with and without quantum memory), on-off photon counting and homodyne (each at different photon power). Finally, we describe two practical applications, one of which cryptographic.
翻译:多存取通道(MAC)由多个发送器组成,同时将其信息传送给一个接收器。对于古典分子(cq-MAC),已知的可实现率假定所有电文都已解码,这是量子网络设计的一个共同假设。然而,这种常规设计方法忽略了全球网络结构,即网络地形学。当将cq-MAC作为量子网络通信的一部分时,这项工作表明,计算特性可以用来提高通信速度,代码设计取决于网络地形。我们量化了计算二发式 cq-MAC属性的代码的可实现的量通信速度。当双发式 cq-MAC是双发式离散调制的双向连贯频道时,我们显示它达到了最大可能的通信速度(单一用户能力),而常规设计无法达到这一速度。此外,这种速度可以通过不同的探测方法实现:量子(有和没有量子内存)、点点数计算和同质体(各有不同光电)等方法。最后,我们描述了两种实用的应用,一种是加密的。