Experimental Simulation of Closed Timelike Curves

Abstract

Closed timelike curves are among the most controversial features of modern physics. As legitimate solutions to Einstein's field equations, they allow for time travel, which instinctively seems paradoxical. However, in the quantum regime these paradoxes can be resolved leaving closed timelike curves consistent with relativity. The study of these systems therefore provides valuable insight into non-linearities and the emergence of causal structures in quantum mechanics-essential for any formulation of a quantum theory of gravity. Here we experimentally simulate the non-linear 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. These include perfect discrimination of non-orthogonal states and, most intriguingly, the ability to distinguish nominally equivalent ways of preparing pure quantum states. Finally, we examine the dependence of these effects on the initial qubit state, the form of the unitary interaction, and the influence of decoherence.

arXiv comment9 pages, 8 figures

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• Theoretical description and experimental simulation of quantum entanglement near open time-like curves via pseudo-density operators
• Closed Timelike Curves, Singularities and Causality: A Survey from Gödel to Chronological Protection
• Homogeneous Gödel-type solutions in hybrid metric-Palatini gravity
• Holographic dual of a time machine
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• Agnostic Phase Estimation
• Simulations of closed timelike curves
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• Spinning up a Time Machine
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• Time travel without paradoxes: Ring resonator as a universal paradigm for looped quantum evolutions
• The D-CTC condition is generically fulfilled in classical (non-quantum) statistical systems
• Analogue time machine in a photonic system
• Revisiting Integer Factorization using Closed Timelike Curves
• Effect of relativistic motion on witnessing non-classicality of quantum states
• Forward-backward stochastic simulations: Q-based model for measurement and Bell-nonlocality consistent with weak local realistic premises
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