Numerical Construction of Multipartite Entanglement Witnesses

Many future quantum technologies rely on the generation of entangled states. Quantum devices will require verification of their operation below some error threshold, but the reliable detection of quantum entanglement remains a considerable challenge for large-scale quantum systems. Well-established techniques for this task rely on the measurement of expectation values of entanglement witnesses, which however require many measurements settings to be extracted. Here we develop a generic framework for efficient entanglement detection that translates any entanglement witness into a resource-efficient probabilistic scheme, whose confidence grows exponentially with the number of individual detection events, namely copies of the quantum state. To benchmark our findings, we experimentally verify the presence of entanglement in a photonic six-qubit cluster state generated using three single-photon sources operating at telecommunication wavelengths. We find that the presence of entanglement can be certified with at least 99:74% confidence by detecting 20 copies of the quantum state. Additionally, we show that genuine six-qubit entanglement is verified with at least 99% confidence by using 112 copies of the state. Our protocol can be carried out with a remarkably low number of copies and in the presence of experimental imperfections, making it a practical and applicable method to verify large-scale quantum devices.

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“…For the biseparable bound we clearly get p bsW 1 = 3/4. For full separability, we used the algorithm presented in [39] to obtain p fsW 1 = 9/16.…”

Section: Methodsmentioning

confidence: 99%

Experimental few-copy multipartite entanglement detection

et al. 2019

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“…The charge described in Table 1 is one among the many that satisfy (12) and has been derived numerically. Explicit procedure for constructing such negative-probability representations have been developed in [73][74][75][76].…”

Section: Tablementioning

confidence: 99%

The Weirdness Theorem and the Origin of Quantum Paradoxes

2021

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We argue that there is a simple, unique, reason for all quantum paradoxes, and that such a reason is not uniquely related to quantum theory. It is rather a mathematical question that arises at the intersection of logic, probability, and computation. We give our ‘weirdness theorem’ that characterises the conditions under which the weirdness will show up. It shows that whenever logic has bounds due to the algorithmic nature of its tasks, then weirdness arises in the special form of negative probabilities or non-classical evaluation functionals. Weirdness is not logical inconsistency, however. It is only the expression of the clash between an unbounded and a bounded view of computation in logic. We discuss the implication of these results for quantum mechanics, arguing in particular that its interpretation should ultimately be computational rather than exclusively physical. We develop in addition a probabilistic theory in the real numbers that exhibits the phenomenon of entanglement, thus concretely showing that the latter is not specific to quantum mechanics.

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“…Several efforts, theoretical and experimental, has been done to improve the methods to make it. The entanglement detection involves a key ingredient: the construction of Entanglement Witness [147,148] . In several practical situations, it is possible to certify entanglement through the violation of some inequality that indicates nonlocality.…”

Section: Detection and Characterization Of Tripartite Entanglementmentioning

confidence: 99%

Tripartite Entanglement: Foundations and Applications

2019

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We review some current ideas about tripartite entanglement, the case representing the next level of complexity beyond the simplest one (though far from trivial), namely the bipartite. This kind of entanglement has an essential role in the understanding of foundations of quantum mechanics. Also, it allows several applications in the fields of quantum information processing and quantum computing. In this paper, we make a revision about the main foundational aspects of tripartite entanglement and we discuss the possibility of using it as a resource to execute quantum protocols. We present some examples of quantum protocols in detail.

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Numerical Construction of Multipartite Entanglement Witnesses

Cited by 22 publications

References 84 publications

Experimental few-copy multipartite entanglement detection

Experimental few-copy multipartite entanglement detection

The Weirdness Theorem and the Origin of Quantum Paradoxes

Tripartite Entanglement: Foundations and Applications

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