发表机构
School of Electrical and Computer Engineering, Cornell University（康奈尔大学电气与计算机工程学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出形成纠缠势方法，证明反馈辅助通信容量界并精确评估振幅阻尼信道，区分单向与双向随机性蒸馏，揭示双向协议通过保留量子关联超越单向极限。
AI 中文摘要
我们发展了用于反馈辅助经典通信和单向随机性蒸馏的形成纠缠势。对于没有初始共享纠缠的有限维量子信道，一个精确的摊销定理界定了消息信息与通信实验室间剩余纠缠之和的增加。这利用Winter和Yang在势容量背景下先前研究的混合凸包络表达式，证明了经典反馈容量界。我们确定了无噪声信道与纠缠破坏信道的标记混合物的容量，改进了已发表的退极化信道逆界，并精确评估了振幅阻尼信道的新界。一个态类比给出了通过单向经典通信可获得净共享随机性的有限块长上界。振幅阻尼Choi态提供了精确基准，而满秩广义振幅阻尼Choi态展示了一个有用的改进，其中我们未精确评估操作速率。我们还区分了单向和双向随机性蒸馏：一个两轮弱测量协议严格超过每个非平凡量子比特各向同性态的精确单向速率。该协议在其第一次解码期间保留量子边信息，并在反向方向提取额外随机性。这解释了为什么单向态势不是一般的双向逆界。总之，这些结果建立了一种基于纠缠的通用方法，以获得更尖锐的通信和随机性界，同时揭示了保留的量子关联如何使双向蒸馏超越单向极限。
英文摘要
We develop entanglement-of-formation potentials for feedback-assisted classical communication and one-way randomness distillation. For a finite-dimensional quantum channel without initial shared entanglement, an exact amortization theorem bounds the increase of message information plus entanglement remaining across the communicating laboratories. This proves a classical-feedback capacity bound using a mixed-convex-roof expression previously studied by Winter and Yang in the context of potential capacities. We determine the capacity of flagged mixtures of noiseless and entanglement-breaking channels, improve a published depolarizing-channel converse, and evaluate the new bound exactly for the amplitude damping channel. A state analogue gives a finite-blocklength upper bound on the net shared randomness obtainable with one-way classical communication. Amplitude-damping Choi states provide exact benchmarks, while a full-rank generalized amplitude-damping Choi state demonstrates a useful improvement where we do not evaluate the operational rate exactly. We also distinguish one-way from two-way randomness distillation: a two-round weak-measurement protocol strictly exceeds the exact one-way rate of every nontrivial qubit isotropic state. The protocol preserves quantum side information during its first decoding and extracts additional randomness in the reverse direction. This shows why the one-way state potential is not a general two-way converse. Together, these results establish a common entanglement-based approach to sharper communication and randomness bounds, while revealing how retained quantum correlations enable two-way distillation to surpass one-way limits.
Comments75 pages, 18 figures
