A relativistic quantum broadcast channel

TL;DR

This paper models a relativistic quantum broadcast channel using a quantum scalar field in curved spacetime, analyzing how classical and quantum information transmission is affected by relativistic effects and causality constraints.

Contribution

It introduces a non-perturbative model for a relativistic quantum broadcast channel with arbitrary states and motions, incorporating causality considerations.

Findings

Derived the channel map in a non-perturbative manner

Analyzed information transmission rates in relativistic settings

Investigated causality effects on communication rates

Abstract

We investigate the transmission of classical and quantum information between three observers in a general globally hyperbolic spacetime using a quantum scalar field as a communication channel. We build a model for a quantum broadcast channel in which one observer (sender) wishes to transmit (classical and quantum) information to two other observers (receivers). They possess some localized two-level quantum system (a qubit) that can interact with the quantum field in order to prepare an input or receive the output of this channel. The field is supposed to be in an arbitrary quasifree state, the three observers may be in arbitrary states of motion, and no choice of representation of the field canonical commutation relations is made. The interaction of the field and qubits is such that it allows us to obtain the map that describes this channel in a non-perturbative manner. We conclude by analyzing the rates at which information can be transmitted through this channel and by investigating relativistic causality effects on such rates.