We analyze utility of communication channels in absence of any short of quantum or classical correlation shared between the sender and the receiver. To this aim, we propose a class of two-party communication games, and show that the games cannot be won given a noiseless $1$-bit classical channel from the sender to the receiver. Interestingly, the goal can be perfectly achieved if the channel is assisted with classical shared randomness. This resembles an advantage similar to the quantum superdense coding phenomenon where pre-shared entanglement can enhance the communication utility of a perfect quantum communication line. Quite surprisingly, we show that a qubit communication without any assistance of classical shared randomness can achieve the goal, and hence establishes a novel quantum advantage in the simplest communication scenario. In pursuit of a deeper origin of this advantage, we show that an advantageous quantum strategy must invoke quantum interference both at the encoding step by the sender and at the decoding step by the receiver. We also study communication utility of a class of non-classical toy systems described by symmetric polygonal state spaces. We come up with communication tasks that can be achieved neither with $1$-bit of classical communication nor by communicating a polygon system, whereas $1$-qubit communication yields a perfect strategy, establishing quantum advantage over them. To this end, we show that the quantum advantages are robust against imperfect encodings-decodings, making the protocols implementable with presently available quantum technologies.

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量子超密编码的经典模拟和单量子系统的通信优势

我们在发送者和接收者之间不存在任何缺乏量子或经典相关性的情况下分析通信通道的效用。为此，我们提出了一类两方通信游戏，并表明，如果从发送方到接收方采用无噪声的 1$ 位经典信道，则无法赢得游戏。有趣的是，如果通道辅以经典的共享随机性，则可以完美实现该目标。这类似于量子超密集编码现象的优点，其中预共享纠缠可以增强完美量子通信线路的通信效用。令人惊讶的是，我们表明，在没有任何经典共享随机性帮助的情况下，量子位通信可以实现这一目标，从而在最简单的通信场景中建立一种新颖的量子优势。为了追求这种优势的更深层次的起源，我们表明，有利的量子策略必须在发送方的编码步骤和接收方的解码步骤中调用量子干扰。我们还研究了由对称多边形状态空间描述的一类非经典玩具系统的通信效用。我们提出的通信任务既不能通过 1 美元比特的经典通信也不能通过多边形系统的通信来实现，而 1 美元量子比特通信则产生了一个完美的策略，建立了相对于它们的量子优势。为此，我们证明了量子优势对于不完美的编码解码具有鲁棒性，使得协议可以使用目前可用的量子技术来实现。