November 2007 - ITP-quantumseminare

Next week's talk (note room)
by Roger Colbeck 30 Nov '07

30 Nov '07

Tuesday 5pm in the meeting room G2 of HPZ (NB not the Pauli room). Ligong will speak on "Applications of Rényi's Entropy of Order $\alpha$" Abstract: I will present some applications (or operational interpretations) of Rényi's Entropy in classical information theory. One application is in one-to-variable source coding problems with an exponential cost function (Campbell 1965). Another application is related to cutoff rates (Csiszár 1995).

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Valerio's lecture
by Renato Renner 27 Nov '07

27 Nov '07

Hi Valerio Scarani will give a lecture on quantum cryptography (as part of Atac Imamoglu and Andreas Wallraff's course on "Quantum Systems for Information Technology"). The lecture is scheduled for Wednesday, November 28, 9.45, in HPT G18 (unfortunately, I did not receive a title or abstract). Cheers Renato

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[QI] QI Seminar
by Dejan D. Dukaric 22 Nov '07

22 Nov '07

Dear All, The next QI Seminar is on Thursday November 29 at 5:00 pm, in IFW E44. Note that we will also shift our "research day" from Tuesday to Thursday next week. Speaker: Valerio Scarani, Centre for Quantum Technologies, National University of Singapore Title: "Reasonable" Models and Quantum Correlations Abstract: The measurement of entangled quantum particles produces outcomes that are correlated, even when the particles are separated by a large distance. There is no doubt on how these correlations should be computed with the formalism of quantum theory; countless experiments have been satisfactorily described by it, and in no case hints of a possible discrepancy have been observed. This looks very much like a textbook case. Nevertheless, these "quantum correlations" are puzzling. Einstein and others already noticed that they cannot originate from communication, since the signal should travel faster than light. In 1964, John Bell found a way of testing the other classical origin, namely pre-established agreement; and subsequent experiments demonstrated that indeed pre-established agreement cannot be invoked either. So, neither of the usual classical causes can explain the observed correlations. In the last years, more sophisticated models have been proposed. These models are "reasonable", in the sense that, while acknowledging that something special is at stake, still try and retain some "intuitive" features. This talk tells the story of these tests, which are helping us to understand quantum physics in greater depth. Suggested readings: For beginners in the field: V. Scarani, Quantum Physics - A First Encounter (Oxford University Press, Oxford, 2006) For experts: C. Branciard, A.Ling, N. Gisin, C. Kurtsiefer, A. Lamas-Linares and V. Scarani, arXiv:0708.0584, to appear in Phys. Rev. Lett.; and references therein. Cheers, Dejan

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Next Tuesday's talk
by Roger Colbeck 15 Nov '07

15 Nov '07

Next Tuesday Daniel will be speaking at 17:00 in the Pauli room of HPZ. Title and Abstract below. Cheers, Roger TITLE: Full control by locally induced relaxation ABSTRACT: We demonstrate a scheme for controlling a large quantum system by acting on a small subsystem only. The local control is mediated to the larger system by some fixed coupling Hamiltonian. The scheme allows to transfer arbitrary and unknown quantum states from a memory on the large system (``upload access'') as well as the inverse (``download access''). We study sufficient conditions of the coupling Hamiltonian and give lower bounds on the fidelities for downloading and uploading.

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[QI] QI Seminar
by Dejan D. Dukaric 09 Nov '07

09 Nov '07

Dear All, The next QI Seminar is on Tuesday, 5:00 pm, in IFW E44. We will have a guest talk by Nicolas Brunner from GAP-Optique at the University of Geneva. Speaker: Nicolas Brunner Title: "Can we see entanglement?" Abstract: According to recent studies, the human eye can detect a signal consisting of very few photons. Though most researchers disagree on the minimal number of photons required (between 3 and 10), there are clear evidences that such a threshold exists. In the context of quantum information, one may wonder whether a non-linear detector such as the eye can be used to detect entanglement, or quantum non-locality. Cheers, Dejan

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[QI] QI Seminar
by Dejan D. Dukaric 05 Nov '07

05 Nov '07

Dear All, Esther's talk will be at 2:00 pm and NOT 5:00 pm tomorrow! See you there, Dejan

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[QI] QI Seminar
by Dejan D. Dukaric 02 Nov '07

02 Nov '07

Dear All, The next QI Seminar is on Tuesday, 5:00 pm, in IFW E44. Speaker: Esther Hänggi Title: "Non-signalling boxes and Quantum Mechanics: similarities and differences" Cheers, Dejan

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