Quantum Information in Relativity: the Challenge of QFT Measurements

TL;DR

This paper discusses the necessity of developing a quantum field theoretic measurement framework to properly understand quantum information in relativistic regimes, addressing foundational issues of causality and locality.

Contribution

It introduces the Quantum Temporal Probabilities program as a practical approach to formulate QFT measurements applicable to relativistic quantum information experiments.

Findings

Identifies foundational problems in QFT measurement theory.

Proposes the Quantum Temporal Probabilities program.

Addresses causality and locality in relativistic quantum measurements.

Abstract

Proposed quantum experiments in deep space will be able to explore quantum information issues in regimes where relativistic effects are important. In this essay, we argue that a proper extension of Quantum Information theory into the relativistic domain requires the expression of all informational notions in terms of quantum field theoretic (QFT) concepts. This task requires a working and practicable theory of QFT measurements. We present the foundational problems in constructing such a theory, especially in relation to longstanding causality and locality issues in the foundations of QFT. Finally, we present the ongoing Quantum Temporal Probabilities program for constructing a measurement theory that (i) works, in principle, for any QFT, (ii) allows for a first-principles investigation of all relevant issues of causality and locality, and (iii) it can be directly applied to experiments of current interest.