利用纠缠输入实现经典通信中无界增益的显式信道
Explicit channels with unbounded gains in classical communication using entangled inputs
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中文总结 AI 辅助
本文构造显式量子信道族，证明仅用输入对内纠缠即可使经典通信速率无界增长，而乘积态速率趋于零，通过确定性Clifford幺正与测量前馈实现去随机化。
中文摘要 AI 辅助
我们构造了一个显式的有限维量子信道族，对于该信道族，使用乘积态码字和集体解码可实现的最优经典通信速率趋于零，而仅利用信道输入对内纠缠所能达到的速率却无界增长。我们的构造将确定性的qudit Clifford幺正变换与二元测量及经典前馈相结合，为Hastings的概率构造提供了一种去随机化方案。关键要素在于精心设计测量与前馈过程，仅通过矩估计即可得到所需的单副本和双副本输出熵界，而无需底层幺正族的强收敛性。
英文摘要
A seminal result of Hastings showed that entangled inputs can increase the rate of classical communication through independent uses of a quantum channel. While Hastings' result proved the existence of this phenomenon, it has remained a major open problem to find an explicit channel with this property. In this work, we resolve this question by constructing an explicit family of finite-dimensional quantum channels for which entangling inputs between pairs of channel uses yields an unbounded separation from the achievable communication rate using unentangled inputs. We describe a circuit implementation of our channel that uses only deterministic qudit Clifford unitaries and a single binary measurement with classical feedforward. The key ingredient is a careful design of the measurement and feedforward process that yields the required one-copy and two-copy output entropy bounds from moment estimates alone, without requiring strong convergence of the underlying unitary family.
发表机构
- National Taiwan University（国立台湾大学）
- National Center for Theoretical Sciences, Taiwan（台湾理论科学中心）
- Hon Hai (Foxconn) Quantum Computing Center, Taiwan（台湾鸿海（富士康）量子计算中心）
- Concordia University（康考迪亚大学）
- Syracuse University（雪城大学）
机构由 AI 辅助整理，请以论文原文为准。
