Single-copy activation of Bell nonlocality via broadcasting of quantum states
Activation of Bell nonlocality refers to the phenomenon that some entangled mixed states that admit a local hidden variable model in the standard Bell scenario nevertheless reveal their nonlocal nature in more exotic measurement scenarios. We present such a scenario that involves broadcasting the lo...
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| Format: | Article |
| Language: | English |
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Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften
2021-07-01
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| Series: | Quantum |
| Online Access: | https://quantum-journal.org/papers/q-2021-07-13-499/pdf/ |
| _version_ | 1818599523628351488 |
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| author | Joseph Bowles Flavien Hirsch Daniel Cavalcanti |
| author_facet | Joseph Bowles Flavien Hirsch Daniel Cavalcanti |
| author_sort | Joseph Bowles |
| collection | DOAJ |
| description | Activation of Bell nonlocality refers to the phenomenon that some entangled mixed states that admit a local hidden variable model in the standard Bell scenario nevertheless reveal their nonlocal nature in more exotic measurement scenarios. We present such a scenario that involves broadcasting the local subsystems of a single-copy of a bipartite quantum state to multiple parties, and use the scenario to study the nonlocal properties of the two-qubit isotropic state:
$
\nonumber \rho_\alpha = \alpha\,|\Phi^+ \rangle\langle \Phi^+|+(1-\alpha)\frac{\mathbb{1}}{4}.
$
We present two main results, considering that Nature allows for (i) the most general no-signalling correlations, and (ii) the most general quantum correlations at the level of any hidden variable theory. We show that the state does not admit a local hidden variable description for $\alpha>0.559$ and $\alpha>\frac{1}{2}$, in cases (i) and (ii) respectively, which in both cases provides a device-independent certification of the entanglement of the state. These bounds are significantly lower than the previously best-known bound of $0.697$ for both Bell nonlocality and device-independent entanglement certification using a single copy of the state. Our results show that strong examples of non-classicality are possible with a small number of resources. |
| first_indexed | 2024-12-16T12:20:57Z |
| format | Article |
| id | doaj.art-121e39ff9a274c0bbb0834c324e2d071 |
| institution | Directory Open Access Journal |
| issn | 2521-327X |
| language | English |
| last_indexed | 2024-12-16T12:20:57Z |
| publishDate | 2021-07-01 |
| publisher | Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften |
| record_format | Article |
| series | Quantum |
| spelling | doaj.art-121e39ff9a274c0bbb0834c324e2d0712022-12-21T22:31:58ZengVerein zur Förderung des Open Access Publizierens in den QuantenwissenschaftenQuantum2521-327X2021-07-01549910.22331/q-2021-07-13-49910.22331/q-2021-07-13-499Single-copy activation of Bell nonlocality via broadcasting of quantum statesJoseph BowlesFlavien HirschDaniel CavalcantiActivation of Bell nonlocality refers to the phenomenon that some entangled mixed states that admit a local hidden variable model in the standard Bell scenario nevertheless reveal their nonlocal nature in more exotic measurement scenarios. We present such a scenario that involves broadcasting the local subsystems of a single-copy of a bipartite quantum state to multiple parties, and use the scenario to study the nonlocal properties of the two-qubit isotropic state: $ \nonumber \rho_\alpha = \alpha\,|\Phi^+ \rangle\langle \Phi^+|+(1-\alpha)\frac{\mathbb{1}}{4}. $ We present two main results, considering that Nature allows for (i) the most general no-signalling correlations, and (ii) the most general quantum correlations at the level of any hidden variable theory. We show that the state does not admit a local hidden variable description for $\alpha>0.559$ and $\alpha>\frac{1}{2}$, in cases (i) and (ii) respectively, which in both cases provides a device-independent certification of the entanglement of the state. These bounds are significantly lower than the previously best-known bound of $0.697$ for both Bell nonlocality and device-independent entanglement certification using a single copy of the state. Our results show that strong examples of non-classicality are possible with a small number of resources.https://quantum-journal.org/papers/q-2021-07-13-499/pdf/ |
| spellingShingle | Joseph Bowles Flavien Hirsch Daniel Cavalcanti Single-copy activation of Bell nonlocality via broadcasting of quantum states Quantum |
| title | Single-copy activation of Bell nonlocality via broadcasting of quantum states |
| title_full | Single-copy activation of Bell nonlocality via broadcasting of quantum states |
| title_fullStr | Single-copy activation of Bell nonlocality via broadcasting of quantum states |
| title_full_unstemmed | Single-copy activation of Bell nonlocality via broadcasting of quantum states |
| title_short | Single-copy activation of Bell nonlocality via broadcasting of quantum states |
| title_sort | single copy activation of bell nonlocality via broadcasting of quantum states |
| url | https://quantum-journal.org/papers/q-2021-07-13-499/pdf/ |
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