量子信道上的经典通信：纠缠在自然界中有帮助吗？
Classical communication over quantum channels: does entanglement help in nature?
Peixue Wu
AI 速览：作者提出Schur加权块熵不等式，证明所有相位协变信道（含多能级振幅阻尼、广义退相位、阻尼-退相位信道）在经典通信中不存在纠缠优势。
Can entangling codewords across independent uses of a quantum channel improve the rate of classical communication? An old conjecture states that there is no such entanglement advantage for all channels. Although Hastings's result and follow-up works disproved this conjecture, it turns out that enormous dimension is required to construct a channel where entanglement enhances classical communication. This indicates that there might be no entanglement advantage for many physical channels, or for all low dimensional channels. Motivated by recent progress on (generalized) amplitude damping channels, we propose a general Schur-weighted block entropy inequality, and show that there is no entanglement advantage for all phase-covariant channels including multi-level amplitude damping channels, generalized dephasing channels, and damping-dephasing channels. As a by-product, we also recover the recently established result that there is no entanglement advantage for all qubit channels.