Titel
Experimental verification of an indefinite causal order
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Abstract
Investigating the role of causal order in quantum mechanics has recently revealed that the causal relations of events may not be a priori well defined in quantum theory. Although this has triggered a growing interest on the theoretical side, creating processes without a causal order is an experimental task. We report the first decisive demonstration of a process with an indefinite causal order. To do this, we quantify how incompatible our setup is with a definite causal order by measuring a “causal witness.” This mathematical object incorporates a series of measurements that are designed to yield a certain outcome only if the process under examination is not consistent with any well-defined causal order. In our experiment, we perform a measurement in a superposition of causal orders—without destroying the coherence—to acquire information both inside and outside of a “causally nonordered process.” Using this information, we experimentally determine a causal witness, demonstrating by almost 7 SDs that the experimentally implemented process does not have a definite causal order.
Stichwort
Quantum InformationQuantum OpticsQuantum Foundations
Objekt-Typ
Sprache
Englisch [eng]
Persistent identifier
https://phaidra.univie.ac.at/o:912586
Erschienen in
Titel
Science Advances
Band
3
Ausgabe
3
Verlag
American Association for the Advancement of Science (AAAS)
Projektnummer
uni:docs – University of Vienna
Projektnummer
W1210-3 – Austrian Science Fund (FWF)
Projektnummer
323714 – European Union (all programmes)
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Erscheinungsdatum
2017
Zugänglichkeit
Rechteangabe
© The Authors

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