Entanglement does not boost classical communication in many quantum channels
Classical communication over quantum channels: does entanglement help in nature?
Information Theory
Summary
The paper looks at whether using quantum entanglement can improve sending ordinary messages through certain quantum channels. While past work showed entanglement can help in very large and complex channels, these situations are rare and may not happen in typical physical systems. The authors prove that for a broad class of quantum channels often seen in practice, entanglement does not increase communication rates. This includes many types of channels that model noise and loss in quantum communication.
What this means in practice
- •For quantum network engineers: Design quantum communication systems knowing entanglement will not increase classical data rate over common noise channels.
- •For quantum hardware developers: Focus resource allocation away from entanglement generation for classical messaging over typical low-dimensional quantum devices.
A theory result. No direct application yet.
Authors
Peixue Wu
Abstract
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.