Centre for Quantum Computer Technology, School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia.
Phys Rev Lett. 2010 May 7;104(18):180503. doi: 10.1103/PhysRevLett.104.180503. Epub 2010 May 6.
Quantum communication typically involves a linear chain of repeater stations, each capable of reliable local quantum computation and connected to their nearest neighbors by unreliable communication links. The communication rate of existing protocols is low as two-way classical communication is used. By using a surface code across the repeater chain and generating Bell pairs between neighboring stations with probability of heralded success greater than 0.65 and fidelity greater than 0.96, we show that two-way communication can be avoided and quantum information can be sent over arbitrary distances with arbitrarily low error at a rate limited only by the local gate speed. This is achieved by using the unreliable Bell pairs to measure nonlocal stabilizers and feeding heralded failure information into post-transmission error correction. Our scheme also applies when the probability of heralded success is arbitrarily low.
量子通信通常涉及一系列线性中继站，每个中继站都能够进行可靠的本地量子计算，并通过不可靠的通信链路与其最近的邻居相连。由于使用了双向经典通信，现有协议的通信速率较低。通过在中继链上使用表面码，并在相邻站点之间以大于 0.65 的成功概率和大于 0.96 的保真度生成贝尔对，我们表明可以避免双向通信，并以仅受本地门速度限制的速率，以任意低的错误率在任意距离上发送量子信息。这是通过使用不可靠的贝尔对来测量非局部稳定器，并将成功的前哨失败信息反馈到传输后纠错中实现的。当成功的前哨概率任意低时，我们的方案也适用。
