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Electronic Colloquium on Computational Complexity

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Reports tagged with time travel:
TR08-092 | 26th August 2008
Scott Aaronson, John Watrous

Closed Timelike Curves Make Quantum and Classical Computing Equivalent

While closed timelike curves (CTCs) are not known to exist, studying their consequences has led to nontrivial insights in general relativity, quantum information, and other areas. In this paper we show that if CTCs existed, then quantum computers would be no more powerful than classical computers: both would have the ... more >>>

TR14-091 | 22nd July 2014
Ryan O'Donnell, A. C. Cem Say

One time-travelling bit is as good as logarithmically many

Revisions: 1

We consider computation in the presence of closed timelike curves (CTCs), as proposed by Deutsch. We focus on the case in which the CTCs carry classical bits (as opposed to qubits). Previously, Aaronson and Watrous showed that computation with polynomially many CTC bits is equivalent in power to PSPACE. On ... more >>>

TR16-146 | 18th September 2016
Scott Aaronson, Mohammad Bavarian, Giulio Gueltrini

Computability Theory of Closed Timelike Curves

We ask, and answer, the question of what's computable by Turing machines equipped with time travel into the past: that is, closed timelike curves or CTCs (with no bound on their size). We focus on a model for CTCs due to Deutsch, which imposes a probabilistic consistency condition to avoid ... more >>>

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