arXiv:1005.2219quant-ph
Closed timelike curves via post-selection: theory and experimental demonstration
Early discovery. Linked by one identifiable commenter. This paper is outside the main ranking; a mention is not an endorsement.
Abstract
Closed timelike curves (CTCs) are trajectories in spacetime that effectively travel backwards in time: a test particle following a CTC can in principle interact with its former self in the past. CTCs appear in many solutions of Einstein's field equations and any future quantum version of general relativity will have to reconcile them with the requirements of quantum mechanics and of quantum field theory. A widely accepted quantum theory of CTCs was proposed by Deutsch. Here we explore an alternative quantum formulation of CTCs and show that it is physically inequivalent to Deutsch's. Because it is based on combining quantum teleportation with post-selection, the predictions/retrodictions of our theory are experimentally testable: we report the results of an experiment demonstrating our theory's resolution of the well-known `grandfather paradox.
I'm loving Scott Aaronson rolling his eyes at this. He actually had a whole section on this in his book for a similar experiment in 2010 on closed timelike curves https://arxiv.org/abs/1005.2219. I feel bad for actual quantum computing experts, we're living through a weird…
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