# Quantum mechanics near closed timelike lines.

@article{Deutsch1991QuantumMN, title={Quantum mechanics near closed timelike lines.}, author={Deutsch}, journal={Physical review. D, Particles and fields}, year={1991}, volume={44 10}, pages={ 3197-3217 } }

The methods of the quantum theory of computation are used to analyze the physics of closed timelike lines. This is dominated, even at the macroscopic level, by quantum mechanics. In classical physics the existence of such lines in a spacetime imposes "paradoxical" constraints on the state of matter in their past and also provides means for knowledge to be created in ways that conflict with the principles of the philosophy of science. In quantum mechanics the first of these pathologies does not…

## 248 Citations

Experimental simulation of closed timelike curves.

- Physics, MedicineNature communications
- 2014

This work experimentally simulate the nonlinear behaviour of a qubit interacting unitarily with an older version of itself, addressing some of the fascinating effects that arise in systems traversing a closed timelike curve.

The breakdown of quantum mechanics in the presence of time machinest

- Physics
- 1993

General Relativity allows for the existence of closed timelike curves. Various attempts have been made to exploit this possibility and build a “time machine,” that is a spacetime that has closed…

Causality violation and nonlinear quantum mechanics

- Physics
- 2013

It is currently unknown whether the laws of physics permit time travel into the past. While general relativity indicates the theoretical possibility of causality violation, it is now widely accepted…

Matters of time directionality in classical and quantum physics

- Physics
- 2016

This report offers a modern perspective on the question of time directionality as it arises in a classical and quantum mechanical context, based on key developments in the field of gravitational…

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…

Quantum causal histories in the light of quantum information

- Physics
- 2007

We use techniques of quantum information theory to analyze the quantum causal histories approach to quantum gravity. While it is consistent to introduce closed timelike curves (CTCs), they cannot…

Open timelike curves violate Heisenberg's uncertainty principle.

- Physics, MedicinePhysical review letters
- 2013

Remarkably, circuits with access to OTCs are shown to violate Heisenberg's uncertainty principle, allowing perfect state discrimination and perfect cloning of coherent states, and the model is extended to wave packets and smoothly recovers standard quantum mechanics in an appropriate physical limit.

Do the laws of physics forbid the operation of time machines?

- Mathematics, Computer ScienceSynthese
- 2008

The verdict on the question of whether it is possible to operate a time machine by manipulating matter and energy so as to manufacture closed timelike curves is that no result of sufficient generality to underwrite a confident “yes” has been proven.

Quantum fields on closed timelike curves

- Physics
- 2011

Recently, there has been much interest in the evolution of quantum particles on closed timelike curves (CTCs). However, such models typically assume pointlike particles with only two degrees of…

Quantum causality in closed timelike curves

- Physics
- 2015

Although general relativity allows the existence of closed timelike curves (CTCs), self-consistency problems arise (the 'grandfather paradox' among others). It is known that quantum mechanical…