Unitary Solution to a Quantum Gravity Information Paradox

TL;DR

This paper presents a toy model demonstrating that a quantum gravity information paradox, arising from apparent non-unitary evolution, can be resolved through a detailed Heisenberg picture analysis revealing underlying unitarity.

Contribution

It introduces a toy model of a qubit interacting with an exotic spacetime, showing that the paradox can be resolved by analyzing the problem in the Heisenberg picture.

Findings

The apparent non-unitary evolution is resolved by a Heisenberg picture analysis.

The model demonstrates that quantum gravity paradoxes may be reconcilable with unitarity.

The analysis provides insights into the nature of information preservation in quantum gravity.

Abstract

We consider a toy model of the interaction of a qubit with an exotic space-time containing a time-like curve. Consistency seems to require that the global evolution of the qubit be non-unitary. Given that quantum mechanics is globally unitary, this then is an example of a quantum gravity information paradox. However, we show that a careful analysis of the problem in the Heisenberg picture reveals an underlying unitarity, thus resolving the paradox.