Replicating the benefits of closed timelike curves without breaking causality

TL;DR

This paper demonstrates that quantum entanglement can replicate the computational and cloning advantages of closed timelike curves without violating causality, revealing new insights into quantum-relativity interplay.

Contribution

It shows that entanglement enables key benefits of closed timelike curves while maintaining causality, challenging previous assumptions about their necessity for such advantages.

Findings

Efficiently solve NP-complete problems using entanglement without time travel.

Clone arbitrary quantum states without causal violations.

Benefits of closed timelike curves can be achieved without causality breaking.

Abstract

In general relativity, closed timelike curves can break causality with remarkable and unsettling consequences. At the classical level, they induce causal paradoxes disturbing enough to motivate conjectures that explicitly prevent their existence. At the quantum level, resolving such paradoxes induce radical benefits - from cloning unknown quantum states to solving problems intractable to quantum computers. Instinctively, one expects these benefits to vanish if causality is respected. Here we show that in harnessing entanglement, we can efficiently solve NP-complete problems and clone arbitrary quantum states - even when all time-travelling systems are completely isolated from the past. Thus, the many defining benefits of closed timelike curves can still be harnessed, even when causality is preserved. Our results unveil the subtle interplay between entanglement and general relativity, and significantly improve the potential of probing the radical effects that may exist at the interface between relativity and quantum theory.