ITP-quantumseminare

itp-quantumseminare@lists.phys.ethz.ch

1 participants
1357 discussions

[QI] QI Seminar
by Dejan D. Dukaric 27 Apr '10

27 Apr '10

Dear All, This weeks research day on Thursday will be at the Computer Science Building CAB. Cyril will present the second part of his talk. Speaker: Cyril Stark Title: From MSA to localization: a rough sketch, part 2 Time: 17:15 pm Place: CAB H 52 Abstract: Multi scale analysis is a method to rigorously prove the existence of localization in specific physical systems. The phenomenon localization occurs in physical systems the dynamics of which is generated by a random Hamilton operator and refers to the following behavior: if the "amount of randomness" is high enough the time evolution of any initial condition will stay within a finite region of space - it localizes. The talk will assume some knowledge about the dynamics of closed quantum systems. Cheers, Dejan

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Seminar this Thursday: Cyril Stark
by Frédéric Dupuis 21 Apr '10

21 Apr '10

Hi everyone, The seminar this week will be given by Cyril Stark. Title: From MSA to localization: a rough sketch Date/Time: Thursday, April 22, 17h15 Place: HIT K 51 Abstract: Multi scale analysis is a method to rigorously prove the existence of localization in specific physical systems. The phenomenon localization occurs in physical systems the dynamics of which is generated by a random Hamlton operator and refers to the following behavior: if the "amount of randomness" is high enough the time evolution of any initial condition will stay within a finite region of space - it localizes. The talk will assume some knowledge about the dynamics of closed quantum systems. Cheers, --Frédéric

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[QI] QI Seminar
by Dejan D. Dukaric 13 Apr '10

13 Apr '10

Dear All, This weeks research day on Thursday will be at the Computer Science Building CAB. Oliver will present his Master Thesis which he did in Renato's group. Speaker: Oliver Marty Title: Squashed entanglement and the antisymmetric state Time: 17:15 pm Place: CAB H 52 Abstract: The first part discusses squashed entanglement and its behavior on the antisymmetric state, which may indicate the existence of entangled states with vanishing squashed entanglement. So far such a situation is only known for the so called bound entangled states of distillable entanglement. In the second part we study the recent concept of separability preserving maps and their relation to different entanglement measures. Cheers, Dejan

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Seminar this Thursday: Now with a real abstract
by Frédéric Dupuis 07 Apr '10

07 Apr '10

Speaker: Lídia del Rio Title: (Quantum) work extraction Date/Time: Thursday, April 8, 17h15 Place: HIT K 51 Abstract: I'll try to give a brief overview of a project we're working on, about how to use the information one observer has about a system to extract work from it without damaging the observer's memory. It should be short and accessible. --Frédéric

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Seminar this Thursday: Lidia del Rio
by Frédéric Dupuis 07 Apr '10

07 Apr '10

Hi everyone, The seminar this week will be given by Lídia del Rio. Title: TBA Date/Time: Thursday, April 8, 17h15 Place: HIT K 51 Abstract: Most scientific concepts, including those involving quantum mechanics, can be summarized in a few lines prior to the occurrence of a talk about them. TBA is the only known exception, a property that has greatly enhanced its popularity in the research community. Come and be surprised. --Frédéric

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[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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ITP-quantumseminare