论文标题
量子和经典数据通过循环顺序叠加的完全去极化通道传输
Quantum and Classical Data Transmission through Completely Depolarising Channels in a Superposition of Cyclic Orders
论文作者
论文摘要
完全疏远的通道通常被视为无用的物理过程的原型：任何沿着明确定义的轨迹传递的信息都被完全消除了。当两个这样的渠道用于两个替代订单的量子叠加中时，它们将能够传输一些经典信息，但是仍然没有量子信息可以通过它们。在这里，我们表明，将n个完全去极化通道放在n个替代因果订单的叠加中的能力使高保真，宣告量子信息的传播，误差消失为1/n。这种现象强调了与n = 2情况下的基本差异，即即使放置在因果秩序的叠加中，完全去极化通道也无法传输量子数据。将量子通道放置在订单叠加中的能力也会导致与n的经典通信能力增加，我们通过得出精确的单个字母表达来严格证明这一点。我们的结果突出了由多个因果秩序引起的更复杂的相关模式，这些模式类似于在多部分量子系统中产生的更复杂的纠缠模式。
Completely depolarising channels are often regarded as the prototype of physical processes that are useless for communication: any message that passes through them along a well-defined trajectory is completely erased. When two such channels are used in a quantum superposition of two alternative orders, they become able to transmit some amount of classical information, but still no quantum information can pass through them. Here we show that the ability to place N completely depolarising channels in a superposition of N alternative causal orders enables a high-fidelity, heralded transmission of quantum information with error vanishing as 1/N. This phenomenon highlights a fundamental difference with the N = 2 case, where completely depolarising channels are unable to transmit quantum data, even when placed in a superposition of causal orders. The ability to place quantum channels in a superposition of orders also leads to an increase of the classical communication capacity with N, which we rigorously prove by deriving an exact single-letter expression. Our results highlight the more complex patterns of correlations arising from multiple causal orders, which are similar to the more complex patterns of entanglement arising in multipartite quantum systems.
