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Experimental superposition of time directions

Abstract : In the macroscopic world, time is intrinsically asymmetric, flowing in a specific direction, from past to future. However, the same is not necessarily true for quantum systems, as some quantum processes produce valid quantum evolutions under time reversal. Supposing that such processes can be probed in both time directions, we can also consider quantum processes probed in a coherent superposition of forwards and backwards time directions. This yields a broader class of quantum processes than the ones considered so far in the literature, including those with indefinite causal order. In this work, we demonstrate for the first time an operation belonging to this new class: the quantum time flip. Using a photonic realisation of this operation, we apply it to a game formulated as a discrimination task between two sets of operators. This game not only serves as a witness of an indefinite time direction, but also allows for a computational advantage over strategies using a fixed time direction, and even those with an indefinite causal order.
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Preprints, Working Papers, ...
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Contributor : Marco Túlio Quintino Connect in order to contact the contributor
Submitted on : Thursday, November 17, 2022 - 6:03:26 PM
Last modification on : Friday, November 18, 2022 - 4:00:10 AM

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  • HAL Id : hal-03858633, version 1
  • ARXIV : 2211.01283


Teodor Strömberg, Peter Schiansky, Marco Túlio Quintino, Michael Antesberger, Lee Rozema, et al.. Experimental superposition of time directions. 2022. ⟨hal-03858633⟩



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