Sending classical information through relativistic quantum channels

TL;DR

This paper explores how relativistic motion affects classical information transmission via quantum channels, demonstrating that relativistic effects can enhance accessible information by exploiting spin-momentum entanglement.

Contribution

It introduces a method to increase classical information transfer in relativistic quantum channels by leveraging spin-momentum entanglement and wave packet width manipulation.

Findings

Relativistic motion can increase accessible information in quantum channels.

Wide momentum wave packets enable better information transfer.

Relativistic effects prevent the channel from being described by completely positive maps.

Abstract

We investigate how special relativity influences the transmission of classical information through quantum channels by evaluating the Holevo bound when the sender and the receiver are in (relativistic) relative motion. By using the spin degrees of freedom of spin-1/2 fermions to encode the classical information we show that, for some configurations, the accessible information in the receiver can be increased when the spin detector moves fast enough. This is possible by allowing the momentum wave packet of one of the particles to be wide enough while the momentum wave packets of other particles are kept relatively narrow. In this way, one can take advantage of the fact that boosts entangle the spin and momentum degrees of freedom of spin-1/2 fermions to increase the accessible information in the former. We close the paper with a discussion of how this relativistic quantum channel cannot in general be described by completely positive quantum maps.