ITP-quantumseminare

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QSIT Lecture: tomorrow October 29, 2010
by Ilona Blatter 28 Oct '10

28 Oct '10

Dear all Additionally to the Colloquium of today evening Ignacio Cirac will give a special lecture for master and PhD students tomorrow morning. With best regards, Ilona Blatter ------------------------------------------------------------------------------------------------------ Date : Friday October 29, 2010 Time: 8:45 – 9:30 Place: HPV G5 Host: A. Imamoglu Efficient Descriptions of Quantum Many-Body Systems A special lecture for master and PhD students presented by Ignacio Cirac Max-Planck-Institut für Quantenoptik, Garching, Germany Coffee and Gipfeli after the lecture ------------------------------------------------------------------------------------------------------ ETH Zurich Dr. Ilona Blatter QSIT Coordinator Laboratory for Solid State Physics HPF E 13 Schafmattstrasse 16 8093 Zurich ilona.blatter(a)phys.ethz.ch www.qsit.ethz.ch Phone: +41 44 633 36 06 Home: +41 44 844 42 50

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Talk by Renato Renner
by Stefan Wolf 25 Oct '10

25 Oct '10

Hi, This week's seminar talk will be given by Renato Renner: Tuesday, Oct. 26, 16:30 in HIT J 52 on Hoenggerberg. Best regards, Stefan _______________________________________________________________ On the non-extendibility of quantum theory Predictions made by quantum theory are generally not deterministic: the theory tells us only how to calculate the probabilities with which measurement outcomes occur. This indeterminism is one of the key differences from classical mechanics and one can ask whether this is the best any theory can offer, or whether observable quantities could be better predicted by some higher theory. We answer this question by showing that quantum theory indeed makes the best possible predictions any theory can possibly make. More precisely, under the assumption that measurement settings can be chosen freely, there cannot exist any extension of quantum theory that provides us with any additional information about the outcomes of future measurements. Joint work with Roger Colbeck (arXiv:1005.5173) _______________________________________________________________

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Talk by Mario Berta
by Stefan Wolf 17 Oct '10

17 Oct '10

Hi, This week's seminar talk will be given by Mario Berta: Tuesday, Oct. 19, 17:00 in CAB H 53 in Zentrum. Best regards, Stefan __________________________________________________________________________ /*The Quantum Reverse Shannon Theorem based on One-Shot Information Theory*/ / / /The Quantum Reverse Shannon Theorem states that any quantum channel can be simulated by an unlimited amount of shared entanglement and an amount of classical communication equal to the channel’s entanglement assisted classical capacity. I will provide a new proof of this theorem, which has previously been proved by Bennett, Devetak, Harrow, Shor, and Winter (arXiv:0912.5537). The proof has a clear structure being based on two recent information-theoretic results: One-Shot Quantum State Merging and the Post-Selection Technique for Quantum Channels./ / / /Joint work with Matthias Christandl and Renato Renner (arXiv:0912.3805). __________________________________________________________________________ /

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Talk by Dejan Dukaric
by Stefan Wolf 06 Oct '10

06 Oct '10

Hi, Next week's seminar talk will be given by Dejan Dukaric, and the speaker chose it to be uphill: Tuesday, Oct. 12, 16:30 in HIT J 52 on Hoenggerberg. Best regards, Stefan _______________________________________________________________ Title: Grothendieck's inequality and maximal violation of Bell inequalities Abstract: I will show how Grothendieck's inequality (in matrix as well as in tensor form) can be used to derive upper bounds on the maximal violation of correlation Bell inequalities (i.e., the Bell inequality depends only on the expectation values). If time permits I will then present a generalized Grothendieck inequality (http://lanl.arxiv.org/abs/1007.3043 and http://lanl.arxiv.org/abs/1008.1948) which can be used to get upper bounds for arbitrary Bell inequalities. _______________________________________________________________

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Talk by Marco Tomamichel
by Stefan Wolf 29 Sep '10

29 Sep '10

Good evening, Next week's seminar talk will be given by Marco Tomamichel: Tuesday, Oct. 5, 16:30 in HIT J 52 on Hoenggerberg. Best regards, Stefan _______________________________________________________________ Title: The Uncertainty Relation for Smooth Entropies Abstract: I will explain our newest uncertainty relation, discuss some of its implications and prove it. Yes, you heard right, prove it. This should be fairly simple and does not require any prior knowledge exceeding what Renato presents in his QIT lecture. _______________________________________________________________

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Talk by Frederic Dupuis
by Stefan Wolf 27 Sep '10

27 Sep '10

Good afternoon, Tomorrow's seminar talk will be given by Frederic Dupuis: Tuesday, Sept. 28, 17:00 in HIT J 52 (J floor!) on Hoenggerberg. Best regards, Stefan _______________________________________________________________ Title: Locking classical correlations into quantum states Abstract: I will show that it is possible to encode a classical message into a quantum state such that, by removing a subsystem of logarithmic size with respect to its total size, no measurement can have significant correlations with the message. The message is therefore "locked" by a key of logarithmic size. I will then show that this has important consequences for security definitions of quantum protocols: if one does not take into account that the adversary can have a quantum memory, this effect can make a "secure" protocol much less secure than one would want. _______________________________________________________________

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Fwd: Seminar by Valerio Scarani, Tue September 21, 2010
by Renato Renner 17 Sep '10

17 Sep '10

Dear all Valerio Scarani will be visiting us next week. After his talk on Monday in the CS department, he will give a second, more physics-oriented talk on Tuesday afternoon (see below). I hope to see many of you there. Best wishes Renato Begin forwarded message: > From: Ilona Blatter <ilona.blatter(a)phys.ethz.ch> > Date: September 17, 2010 12:14:47 GMT+02:00 > To: <qsit-announce(a)phys.ethz.ch> > Subject: Seminar by Valerio Scarani, Tue September 21, 2010 > > Dear all > > Please be informed about the following sminar. > > With best regards, > Ilona > --------------------------------------------------- > Date: Tuesday September 21, 2010 > Time: 17:15 > Place: HIT E 41.1 > Host: Renato Renner > > Practical quantum cryptography: recent progresses > Valerio Scarani > National University of Singapore, Singapore > > Abstract: > Some time ago, I co-authored a review article on practical quantum cryptography [1]. The field has not stopped progressing since then. I shall sketch the initial developments as presented in [1], for the sake of those who are not familiar with them; then I shall present the more recent results and suggest some ideas for the future. > > [1] V.S. et al., Rev. Mod. Phys. 81, 1301 (2009) > > > > > --------------------------------------------------- > ETH Zurich > Dr. Ilona Blatter > QSIT Coordinator > Laboratory for Solid State Physics > HPF E 13 > Schafmattstrasse 16 > 8093 Zurich > > ilona.blatter(a)phys.ethz.ch > www.qsit.ethz.ch > > Phone: +41 44 633 36 06 > Home: +41 44 844 42 50 >

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Two Talks on Applied Mathematics and Complexity Theory: Change of Location
by Matthias Christandl 07 Sep '10

07 Sep '10

Dear all, please note the change of location for the second talk next week: > Dear all, > > next week Peter Bürgisser from Paderborn is visiting us. He will give two talks on applied mathematics and complexity theory. Please see below for the announcements. > > All the best, > > Matthias. > > Matthias Christandl > Institute for Theoretical Physics > ETH Zurich > http://www.itp.phys.ethz.ch/people/christandl/index > > ---------------------------------------------------------------------------------------------- > Speaker: Peter Bürgisser (University of Paderborn) > > Time and Location: Tuesday, 14th of September, 11am, HG F 33.1 (ETH Zentrum) > > Title: Smoothed analysis of condition numbers > > Abstract: We present some recent results on the probabilistic behaviour of interior point methods for the convex conic feasibility problem and for homotopy methods solving complex polynomial equations. As suggested by Spielman and Teng, the goal is to prove that for all inputs (even ill-posed ones), and all slight random perturbations of that input, it is unlikely that the running time will be large. These results are obtained through a probabilistic analysis of the condition of the corresponding computational problems. > > > ---------------------------------------------------------------------------------------------- > Speaker: Peter Bürgisser (University of Paderborn) > > Time and Location: Thursday, 16th of September, 11am, HPK D 24.2 (ETH Hönggerberg) > > Title: The state of the art in geometric complexity theory > > Abstract: Geometric complexity theory is an approach towards the fundamental lower bound problems in complexity theory based on algebraic geometry and representation theory. Originally, it has been proposed for the permanent versus determinant problem. Recently, the overall framework has been applied and further developed for the tensor rank problem (complexity of matrix multiplication). While no good lower bounds have been obtained so far with these methods, we have now a much clearer understanding of the mathematical difficulties to be overcome for advancing. > > Matthias Christandl Institute for Theoretical Physics ETH Zurich http://www.itp.phys.ethz.ch/people/christandl/index

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Two Talks on Applied Mathematics and Complexity Theory
by Matthias Christandl 06 Sep '10

06 Sep '10

Dear all, next week Peter Bürgisser from Paderborn is visiting us. He will give two talks on applied mathematics and complexity theory. Please see below for the announcements. All the best, Matthias. Matthias Christandl Institute for Theoretical Physics ETH Zurich http://www.itp.phys.ethz.ch/people/christandl/index ---------------------------------------------------------------------------------------------- Speaker: Peter Bürgisser (University of Paderborn) Time and Location: Tuesday, 14th of September, 11am, HG F 33.1 (ETH Zentrum) Title: Smoothed analysis of condition numbers Abstract: We present some recent results on the probabilistic behaviour of interior point methods for the convex conic feasibility problem and for homotopy methods solving complex polynomial equations. As suggested by Spielman and Teng, the goal is to prove that for all inputs (even ill-posed ones), and all slight random perturbations of that input, it is unlikely that the running time will be large. These results are obtained through a probabilistic analysis of the condition of the corresponding computational problems. ---------------------------------------------------------------------------------------------- Speaker: Peter Bürgisser (University of Paderborn) Time and Location: Thursday, 16th of September, 11am, HIT K 51 (ETH Hönggerberg) Title: The state of the art in geometric complexity theory Abstract: Geometric complexity theory is an approach towards the fundamental lower bound problems in complexity theory based on algebraic geometry and representation theory. Originally, it has been proposed for the permanent versus determinant problem. Recently, the overall framework has been applied and further developed for the tensor rank problem (complexity of matrix multiplication). While no good lower bounds have been obtained so far with these methods, we have now a much clearer understanding of the mathematical difficulties to be overcome for advancing.

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quantum information seminar
by Matthias Christandl 25 Aug '10

25 Aug '10

Dear all, On Monday next week, Oleg Szehr will present his semester project Time and Location: Monday, August 30, 11.00, HIT K51 Title: Quantum coding via the decoupling approach Abstract: The talk focuses on the decoupling approach to quantum coding. The aim is to show a strong quantum coding theorem, which arises from an application of the decoupling theorem. A rough overview of the technical proofs of i) The Decouping Theorem, ii) The smoothed Decoupling Theorem, iii) The quantum Coding Theorem, is given. I hope to see many of you there. Best wishes Matthias.

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ITP-quantumseminare