Universität zu Köln

Bavaresco, Jessica, Araujo, Mateus, Brukner, Caslav and Quintino, Marco Tulio (2019). Semi-device-independent certification of indefinite causal order. Quantum, 3. WIEN: VEREIN FORDERUNG OPEN ACCESS PUBLIZIERENS QUANTENWISSENSCHAF. ISSN 2521-327X

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Abstract

When transforming pairs of independent quantum operations according to the fundamental rules of quantum theory, an intriguing phenomenon emerges: some such higher-order operations may act on the input operations in an indefinite causal order. Recently, the formalism of process matrices has been developed to investigate these noncausal properties of higher-order operations. This formalism predicts, in principle, statistics that ensure indefinite causal order even in a device-independent scenario, where the involved operations are not characterised. Nevertheless, all physical implementations of process matrices proposed so far require full characterisation of the involved operations in order to certify such phenomena. Here we consider a semi-device-independent scenario, which does not require all operations to be characterised. We introduce a framework for certifying noncausal properties of process matrices in this intermediate regime and use it to analyse the quantum switch, a well-known higher-order operation, to show that, although it can only lead to causal statistics in a device-independent scenario, it can exhibit noncausal properties in semi-device-independent scenarios. This proves that the quantum switch generates stronger noncausal correlations than it was previously known.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Bavaresco, Jessica UNSPECIFIED UNSPECIFIED UNSPECIFIED Araujo, Mateus UNSPECIFIED UNSPECIFIED UNSPECIFIED Brukner, Caslav UNSPECIFIED UNSPECIFIED UNSPECIFIED Quintino, Marco Tulio UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-144537
Journal or Publication Title:	Quantum
Volume:	3
Date:	2019
Publisher:	VEREIN FORDERUNG OPEN ACCESS PUBLIZIERENS QUANTENWISSENSCHAF
Place of Publication:	WIEN
ISSN:	2521-327X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language QUANTUM; VIOLATION; STATES Multiple languages Quantum Science & Technology; Physics, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/14453