# Treating Time Travel Quantum Mechanically

@article{Allen2014TreatingTT, title={Treating Time Travel Quantum Mechanically}, author={John-Mark Allen}, journal={Physical Review A}, year={2014}, volume={90}, pages={042107} }

The fact that closed timelike curves (CTCs) are permitted by general relativity raises the question as to how quantum systems behave when time travel to the past occurs. Research into answering this question by utilising the quantum circuit formalism has given rise to two theories: Deutschian-CTCs (D-CTCs) and "postselected" CTCs (P-CTCs). In this paper the quantum circuit approach is thoroughly reviewed, and the strengths and shortcomings of D-CTCs and P-CTCs are presented in view of their non…

## 19 Citations

Closed timelike curves and the second law of thermodynamics

- PhysicsPhysical Review A
- 2019

One out of many emerging implications from solutions of Einstein's general relativity equations are closed timelike curves (CTCs), which are trajectories through spacetime that loop back on…

Categorical Semantics for Time Travel

- Computer Science2019 34th Annual ACM/IEEE Symposium on Logic in Computer Science (LICS)
- 2019

A general categorical framework to reason about quantum theory and other process theories living in spacetimes where chronology violation can occur, and provides the first compositional description of the D-CTC model.

Simulations of Closed Timelike Curves

- Computer Science
- 2017

It is proved that the recently proposed transition probability CTCs (T-CTCs) are physically equivalent to postselection C TCs (P-CTs), in the sense that one model can simulate the other with reasonable overhead.

Replicating the benefits of Deutschian closed timelike curves without breaking causality

- Physics
- 2015

Investigation of closed timelike curves showed that despite such restrictions, OTCs allow quantum computers to clone quantum states, defy Heisenberg’s uncertainty principle, and efficiently solve previously intractable mathematical problems.

The D-CTC Condition is Generically Fulfilled in Classical (Non-quantum) Statistical Systems

- PhysicsFoundations of Physics
- 2021

The D-CTC condition, introduced by David Deutsch as a condition to be fulfilled by analogues for processes of quantum systems in the presence of closed timelike curves, is investigated for classical…

Computation in generalised probabilistic theories

- MathematicsArXiv
- 2014

This work defines a circuit-based model of computation in a class of operationally-defined theories more general than quantum theory, and shows there exists a classical oracle relative to which efficient computation in any theory satisfying the causality assumption does not include .

Reality, causality, and quantum theory

- Philosophy
- 2017

Quantum theory describes our universe incredibly successfully. To our classically-inclined brains, however, it is a bizarre description that requires a reimagining of what fundamental reality, or…

Dynamics of quantum causal structures

- Philosophy
- 2017

This work develops a framework for "dynamics of causal structures", i.e. for transformations of process matrices into process Matrices, and shows that, under continuous and reversible transformations, the causal order between operations is always preserved.

Bounds on computation from physical principles

- Computer Science
- 2017

This thesis defines a circuit-based model of computation in the operationally-defined framework of generalised probabilistic theories and investigates the relationship between interference behaviour and computational power, demonstrating that non-trivial interference behaviour is a general resource for post-classical computation.

Timelike curves can increase entanglement with LOCC

- PhysicsScientific reports
- 2016

This work studies the nature of entanglement in presence of Deutschian closed timelike curves and shows how D-CTCs and OTCs can unambiguously distinguish between four Bell states with LOCC, that is otherwise known to be impossible.

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