March 2010 - ITP-quantumseminare

[QI] QI Seminar
by Dejan D. Dukaric 30 Mar '10

30 Mar '10

Dear All, This weeks research day on Thursday will be at the Computer Science Building CAB. Speaker: Stefan Wolf Title: Bell Inequalities Without Quantum Advantage Time: 17:15 pm Place: CAB H 52 Abstract: It has been an open problem -- no. 26 of Reinhard Werner's collection -- whether there exists a Bell inequality that - defines a face of the local polytope, - cannot be violated by quantum physics, but - can be violated by a non-signaling strategy. We discuss an affirmative answer to the question given by Almeida, Bancal, Brunner, Acin, Gisin, and Pironio. Cheers, Dejan

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Seminar this Thursday: Renato Renner
by Frédéric Dupuis 23 Mar '10

23 Mar '10

Hi all, Our next seminar will take place this Thursday (March 25) at 17h15 in HIT K51. Speaker: Renato Renner Title: Min-entropy sampling See you there! --Frédéric

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[QI] QI Seminar
by Dejan D. Dukaric 17 Mar '10

17 Mar '10

Dear All, This weeks research day on Thursday will be at the Computer Science Building CAB. Speaker: Johan Aaberg Title: Something Time: 17:15 pm Place: CAB H 53 Cheers, Dejan

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talks this week
by Roger Colbeck 07 Mar '10

07 Mar '10

Hi all, This week's talk will be by Severin and is on Thursday in HIT K51 at 17:15 (title and abstract below). Also, a reminder that there is an additional talk this Tuesday by Hans Christian Oettinger at 15:00 in HIT J52. Cheers, Roger --- The talk presents results from a project with Juerg Wullschleger "On the Efficiency of Classical and Quantum Oblivious Transfer Reductions". Familiarity with concepts from secure two-party computation is assumed - and this time there is a relation to quantum information theory :-) : In the first part of the talk I will shortly present lower bounds on the efficiency of statistically secure classical protocols implementing 1-out-of-n Oblivous Transfer (OT) from (trusted) distributed randomness, i.e., bounds on the minimal number of instances of a given primitive needed to implement OT. (seminar talk of December 8 or http://eprint.iacr.org/2009/508: Statistical Impossiblity Results for Oblivous Transfer Reductions). Then I will present a statistically secure quantum protocol implementing OT that is more efficient than any /statistical /implementation in the classical case and any /perfect/ implementation in the quantum case (by an arbitrarily large factor). I will then present a weaker lower bound that holds for statistically secure implementations of OT in the quantum setting. In particular this bound can be used to show that even quantum protocols /cannot/ extend OT. See full abstract below. Abstract: Due to its universality oblivious transfer (OT) is a primitive of great importance in secure multi-party computation. OT is impossible to implement from scratch in an unconditionally secure way, but there are many reductions of OT to other variants of OT, as well as other primitives such as noisy channels. It is important to know how efficient such unconditionally secure reductions can be in principle, i.e., how many instances of a given primitive are at least needed to implement OT. For perfect (error-free) implementations good lower bounds are known, e.g. the bounds by Beaver (STOC ’96) or by Dodis and Micali (EUROCRYPT ’99). But since in practice one is usually willing to tolerate a small probability of error and since these statistical reductions can be much more efficient, the known bounds have only limited application. In the first part of this work we provide lower bounds on the efficiency of 1-out-of-n OT and Rabin-OT reductions to distributed randomness in the statistical case. From these results we derive bounds on reductions to different variants of OT that generalize known bounds to the statistical case. Our bounds hold in particular for transformations between a finite number of primitives and for any error. In the second part we look at the efficiency of quantum reductions. Recently, Salvail, Schaffner and Sotakova (ASIACRYPT ’09) showed that most classical lower bounds for perfectly secure reductions of OT to distributed randomness still hold in a quantum setting. We present a statistically secure protocol that violates these bounds by an arbitrarily large factor. We then present a weaker lower bound for the statistical setting. We use this bound to show that even quantum protocols cannot extend OT. Finally, we present two lower bounds for reductions of OT to commitments and a protocol based on string commitments that is optimal with respect to both of these bounds.

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[QI] QI Seminar
by Dejan D. Dukaric 04 Mar '10

04 Mar '10

Dear All, Todays talks is given by Oscar. Speaker: Oscar Dahlsten Title: TBA Time: 5:15 pm Place: CAB H 53 Abstract: TBA Cheers, Dejan

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Fwd: Call for Registrations: The Seventh Annual Canadian Quantum Information Students' Conference
by Frédéric Dupuis 02 Mar '10

02 Mar '10

Dear Colleagues, This is a call for registrations for The Seventh Annual Canadian Quantum Information Students' Conference (CQISC) hosted by the Institute for Quantum Information Science (IQIS) at the University of Calgary from July 12-16 2010. Complete details can be found at http://www.iqis.org/events/cqisc10/ Highlights Include: Accommodation subsidy for external attendees Registration for this conference is free and attendees traveling from outside of Calgary can apply for a fully subsidized 6 nights accommodation (Sunday-Friday). Breakfast and refreshments will also be provided on conference days (July 12-16). Transportation discount Delegates making the trip to CQISC are eligible for a 10% discount on Westjet flights to Calgary. For further information please consult the conference webpage. Calgary Stampede As a bonus, this year's CQISC will be held at the same time as the greatest outdoor show on earth, the Calgary Stampede. This annual event attracts 1 million tourists to the Calgary area. CQISC attendees will have the benefit of experiencing the Stampede without enduring the high cost of hotels in the city. QuNO'10 A portion of CQISC'10 will also serve as the second annual Alberta Quantum Nano-Optics (QuNO) 2010 meeting. The goal is to have a gathering of graduate students to communicate skills that would be constructive for day-to-day research. Please indicate on the registration form, if you are interested in presenting a talk during QuNO'10. Conference Activities A conference outing will be scheduled on the Saturday following the conference. Calgary also provides a wealth of activities to take part in during your stay, including hiking, camping, horseback riding, rafting, climbing, caving, and stampeding!. The conference will also feature a banquet and prizes for best talks and posters. If you have anymore questions or concerns please do not hesitate to contact myself or the principal organizer, our complete contact info can be found from the link. I look forward to seeing you in July! Sincerely, Connor Kupchak CQISC Advertising Coordinator

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new times for the talks
by Roger Colbeck 01 Mar '10

01 Mar '10

Hi all, Last week we decided that the talks will now be held on Thursdays at 17:15. This week's talk will be by Oscar in CAB at the new time. Also, next Tuesday (9th) we have an additional talk by Hans Christian Oettinger at 15:00 in HIT *J52* Title: Dissipative quantum systems from a nonequilibrium thermodynamicist's perspective Abstract: I present modern nonequilibrium thermodynamics with a strong emphasis on the underlying geometric ideas and concepts. The geometric structures are then used as a key to finding a generalization from classical to quantum systems. This generalization step is supported by the "principle of beauty." Whereas linearity is natural in quantum mechanics, it is rather unusual in thermodynamics (because of the presence of entropy). Accordingly, the thermodynamic quantum maser equation resulting from the geometric generalization is nonlinear (and hence not of the familiar Lindblad form). This nonlinearity improves the behavior of the solutions. I illustrate the general ideas mainly in the context of the two-level system of quantum optics or NMR. Cheers, Roger

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