Discontinuous quantum evolutions in the presence of closed timelike curves

TL;DR

This paper investigates Deutsch's quantum model with closed timelike curves, revealing that it predicts discontinuous evolutions of quantum states, which remain even under natural modifications of the model.

Contribution

It demonstrates that Deutsch's model leads to discontinuous quantum evolutions, highlighting a fundamental non-linearity and non-unitarity in such spacetimes.

Findings

Discontinuous state evolutions occur in Deutsch's model with closed timelike curves

Discontinuities persist despite modifications to the original approach

The model exhibits non-linear and non-unitary behavior in these scenarios

Abstract

We consider Deutsch's computational model of a quantum system evolving in a spacetime containing closed timelike curves. Although it is known that this model predicts non-linear and non-unitary evolutions of the system, we demonstrate that it also gives rise to evolutions which are a discontinuous function of the input state. These discontinuities persist for the most natural modifications of Deutsch's approach.