Communication over a quantum broadcast channel with cooperation between the receivers is considered. The first form of cooperation addressed is classical conferencing, where Receiver 1 can send classical messages to Receiver 2. Another cooperation setting involves quantum conferencing, where Receiver 1 can teleport a quantum state to Receiver 2. When Receiver 1 is not required to recover information and its sole purpose is to help the transmission to Receiver 2, the model reduces to the quantum primitive relay channel. The quantum conferencing setting is intimately related to quantum repeaters, as the sender, Receiver 1, and Receiver 2 can be viewed as the transmitter, the repeater, and the destination receiver, respectively. We develop lower and upper bounds on the capacity region in each setting. In particular, the cutset upper bound and the decode-forward lower bound are derived for the primitive relay channel. Furthermore, we present an entanglement-formation lower bound, where a virtual channel is simulated through the conference link. At last, we show that as opposed to the multiple access channel with entangled encoders, entanglement between decoders does not increase the classical communication rates for the broadcast dual.

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具有协作解码器的量子广播信道：关于量子中继器的信息论观点

考虑在接收器之间协作的量子广播信道上的通信。第一种合作形式是经典会议，其中接收方 1 可以向接收方 2 发送经典消息。另一种合作设置涉及量子会议，其中接收方 1 可以将量子状态传送到接收方 2。当不需要接收方 1 恢复信息和它的唯一目的是帮助传输到接收器 2，该模型简化为量子原始中继通道。量子会议设置与量子中继器密切相关，因为发送器、接收器 1 和接收器 2 可以分别被视为发送器、中继器和目标接收器。我们在每个设置中开发容量区域的下限和上限。特别是，为原始中继信道导出割集上限和解码前向下限。此外，我们提出了一个纠缠形成下界，其中通过会议链接模拟了一个虚拟通道。最后，我们表明，与具有纠缠编码器的多址信道相反，解码器之间的纠缠不会增加广播对偶的经典通信速率。