| 1. |
- Ahrens, Johan, et al.
(författare)
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Experimental Tests of Classical and Quantum Dimensionality
- 2014
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 112:14
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Tidskriftsartikel (refereegranskat)abstract
- We report on an experimental test of classical and quantum dimension. We have used a dimension witness that can distinguish between quantum and classical systems of dimensions two, three, and four and performed the experiment for all five cases. The witness we have chosen is a base of semi-device-independent cryptographic and randomness expansion protocols. Therefore, the part of the experiment in which qubits were used is a realization of these protocols. In our work we also present an analytic method for finding the maximum quantum value of the witness along with corresponding measurements and preparations. This method is quite general and can be applied to any linear dimension witness.
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| 2. |
- Muhammad, Sadiq, et al.
(författare)
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Quantum Bidding in Bridge
- 2014
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Ingår i: Physical Review X. - 2160-3308. ; 4:2
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Tidskriftsartikel (refereegranskat)abstract
- Quantum methods allow us to reduce communication complexity of some computational tasks, with several separated partners, beyond classical constraints. Nevertheless, experimental demonstrations of this have thus far been limited to some abstract problems, far away from real-life tasks. We show here, and demonstrate experimentally, that the power of reduction of communication complexity can be harnessed to gain an advantage in a famous, immensely popular, card game-bridge. The essence of a winning strategy in bridge is efficient communication between the partners. The rules of the game allow only a specific form of communication, of very low complexity (effectively, one has strong limitations on the number of exchanged bits). Surprisingly, our quantum technique does not violate the existing rules of the game (as there is no increase in information flow). We show that our quantum bridge auction corresponds to a biased nonlocal Clauser-Horne-Shimony-Holt game, which is equivalent to a 2 -> 1 quantum random access code. Thus, our experiment is also a realization of such protocols. However, this correspondence is not complete, which enables the bridge players to have efficient strategies regardless of the quality of their detectors.
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| 3. |
- Radmark, Magnus, et al.
(författare)
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Experimental multilocation remote state preparation
- 2013
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 88:3, s. 032304-
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Tidskriftsartikel (refereegranskat)abstract
- Transmission of quantum states is a central task in quantum information science. Remote state preparation (RSP) has the same goal as teleportation, i.e., transferring quantum information without sending physically the information carrier, but in RSP the sender knows the state which is to be transmitted. We present experimental demonstrations of RSP for two and three locations. In our experimental scheme Alice (the preparer) and her three partners share four and six photon polarization entangled singlets. This allows us to perform RSP of two or three copies of a single-qubit state, a two-qubit Bell state, and a three-qubit W, or (W) over bar state. A possibility to prepare two-qubit nonmaximally entangled and GHZ states is also discussed. The ability to remotely prepare an entangled states by local projections at Alice is a distinguishing feature of our scheme.
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| 4. |
- Trojek, Pavel, et al.
(författare)
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Experimental multipartner quantum communication complexity employing just one qubit
- 2013
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Ingår i: Natural Computing. - : Springer Science and Business Media LLC. - 1567-7818 .- 1572-9796. ; 12:1, s. 19-26
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Tidskriftsartikel (refereegranskat)abstract
- Most proposals for quantum solutions of information-theoretic problems rely on the usage of multi-partite entangled states which are still difficult to produce experimentally with current state-of-the-art technology. Here, we analyze a scheme to simplify a particular kind of multiparty communication protocols for the experiment. We prove that the fidelity of two communication complexity protocols, allowing for an N - 1 bit communication, can be exponentially improved by N - 1 (unentangled) qubit communication. Taking into account, for a fair comparison, all inefficiencies of state-of-the-art set-up, the experimental implementation for N = 5 outperforms the best classical protocol, making it the candidate for multi-party quantum communication applications.
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