Experimental superposition of time directions

Fuente: arXiv
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Autores principales: Strömberg, Teodor, Schiansky, Peter, Quintino, Marco Túlio, Antesberger, Michael, Rozema, Lee, Agresti, Iris, Brukner, Časlav, Walther, Philip
Formato: Preprint
Publicado: 2022
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author Strömberg, Teodor
Schiansky, Peter
Quintino, Marco Túlio
Antesberger, Michael
Rozema, Lee
Agresti, Iris
Brukner, Časlav
Walther, Philip
author_facet Strömberg, Teodor
Schiansky, Peter
Quintino, Marco Túlio
Antesberger, Michael
Rozema, Lee
Agresti, Iris
Brukner, Časlav
Walther, Philip
contents 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.
format Preprint
id arxiv_https___arxiv_org_abs_2211_01283
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Experimental superposition of time directions
Strömberg, Teodor
Schiansky, Peter
Quintino, Marco Túlio
Antesberger, Michael
Rozema, Lee
Agresti, Iris
Brukner, Časlav
Walther, Philip
Quantum Physics
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.
title Experimental superposition of time directions
topic Quantum Physics
url https://arxiv.org/abs/2211.01283