| 1. |
- Amselem, Elias, et al.
(författare)
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State-Independent Quantum Contextuality with Single Photons
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:160405
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Tidskriftsartikel (refereegranskat)abstract
- Wepresent an experimental state-independent violation of an inequality for noncontextualtheories on single particles. We show that 20 different single-photonstates violate an inequality which involves correlations between results ofsequential compatible measurements by at least 419 standard deviations. Ourresults show that, for any physical system, even for asingle system, and independent of its state, there is auniversal set of tests whose results do not admit anoncontextual interpretation. This sheds new light on the role ofquantum mechanics in quantum information processing.
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| 2. |
- Bengtsson, Ingemar, et al.
(författare)
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Universality of State-Independent Violation of Correlation Inequalities for Non-Contextual Theories
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:5, s. 050401-
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Tidskriftsartikel (refereegranskat)abstract
- We show that the state-independent violation of inequalities for noncontextual hidden variable theories introduced in [Phys. Rev. Lett. 101, 210401 (2008)] is universal, i.e., occurs for any quantum mechanical system in which noncontextuality is meaningful. We describe a method to obtain state-independent violations for any system of dimension d >= 3. This universality proves that, according to quantum mechanics, there are no "classical'' states.
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| 3. |
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| 4. |
- Cabello, Adan, et al.
(författare)
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Minimum Detection Efficiency for a Loophole-Free Atom-Photon Bell Experiment
- 2007
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 98, s. 220402-1-220402-4
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Tidskriftsartikel (refereegranskat)abstract
- In Bell experiments, one problem is to achieve high enough photodetection to ensure that there is no possibility of describing the results via a local hidden-variable model. Using the Clauser-Horne inequality and a two-photon nonmaximally entangled state, a photodetection efficiency higher than 0.67 is necessary. Here we discuss atom-photon Bell experiments. We show that, assuming perfect detection efficiency of the atom, it is possible to perform a loophole-free atom-photon Bell experiment whenever the photodetection efficiency exceeds 0.50.
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| 5. |
- Cabello, Adan, et al.
(författare)
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Minimum detection efficiency required for a loophole-free violation of the Braunstein-Caves chained Bell inequalities
- 2009
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : American Physical Society. - 1050-2947 .- 1094-1622. ; 79:6, s. 062109-1-062109-7
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Tidskriftsartikel (refereegranskat)abstract
- The chained Bell inequalities of Braunstein and Caves involving N settings per observer have some interesting applications. Here we obtain the minimum detection efficiency required for a loophole-free violation of the Braunstein-Caves inequalities for any N greater than= 2. We discuss both the case in which both particles are detected with the same efficiency and the case in which the particles are detected with different efficiencies.
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| 6. |
- Gaertner, Sascha, et al.
(författare)
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Experimental demonstration of a quantum protocol for byzantine agreement and liar detection
- 2008
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 100:7, s. 70504-
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a new quantum protocol for solving detectable Byzantine agreement (also called detectable broadcast) between three parties, and also for solving the detectable liar detection problem. The protocol is suggested by the properties of a four-qubit entangled state, and the classical part of the protocol is simpler than that of previous proposals. In addition, we present an experimental implementation of the protocol using four-photon entanglement.
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