August 2012 - ITP-quantumseminare

QSIT Lunch Seminar and iPad tombola, Thursday September 6, 2012
by QSIT Seminar 31 Aug '12

31 Aug '12

Dear QSIT members The next QSIT Lunch Seminar will take place on Thursday September 6, 2012, at 12:00 noon in the room HPF G6, ETH Hönggerberg, Zurich. There will be two talks of 30 minutes duration jointly presented by two collaborators from different research groups. At 13:00 pm free pizza is offered to the participants. Furthermore at this occasion the winner of the iPad will be drawn! Magnetic states of individual ferromagnetic nanotube probed by anisotropic magnetoresistance Daniel Rüffer Laboratory of Semiconductor Materials, EPFL and Ultra-High Quality Factor Single-Crystal Diamond Nanoresonator Ye Tao Spin Physics and Imaging - Degen Lab, ETHZ Abstracts: http://www.nccr-qsit.ethz.ch/news/lunchseminar/september2012 Please register for your free pizza at the following link by Tuesday September 4, 12:00 noon: https://ethz.doodle.com/t8p4m4wf4zsw3dah If you have suggestions on topics or speakers, or would like to present recent results of your research, please send your information to Andreas Wallraff or Ilona Blatter. With best regards, Andreas Wallraff Ilona Blatter Professor for Solid State Physics QSIT Coordinator ------------------------------------------------------------------ ETH Zurich Dr. Ilona Blatter NCCR QSIT Coordinator Laboratory for Solid State Physics HPF E 17 Schafmattstrasse 16 8093 Zurich ilona.blatter(a)phys.ethz.ch www.nccr-qsit.ethz.ch Phone: +41 44 633 36 06

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QSIT Seminar by Sophia Economou, Friday August 31, 2012
by QSIT Seminar 29 Aug '12

29 Aug '12

Dear all Please be informed about the following QSIT Seminar. With best regards, Ilona Blatter --------------------------------------------------- Date: Friday, August 31, 2012 Time: 11:00 Place: HPF G 6 Host: Atac Imamoglu Optically controlled spins in quantum dots Sophia Economou Naval Research Labs, USA Abstract: http://www.nccr-qsit.ethz.ch/news/talks/abstractEconomou --------------------------------------------------- ETH Zurich Dr. Ilona Blatter NCCR QSIT Coordinator Laboratory for Solid State Physics HPF E 17 Schafmattstrasse 16 8093 Zurich ilona.blatter(a)phys.ethz.ch www.nccr-qsit.ethz.ch Phone: +41 44 633 36 06 ------------------------------------------------------------------------------------------------------ ETH Zurich Dr. Ilona Blatter NCCR QSIT Coordinator Laboratory for Solid State Physics HPF E 17 Schafmattstrasse 16 8093 Zurich ilona.blatter(a)phys.ethz.ch www.nccr-qsit.ethz.ch Phone: +41 44 633 36 06

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Group Meeting August 28th
by Normand Beaudry 27 Aug '12

27 Aug '12

Dear all, Tomorrow's group meeting will be in HIT E 41.1 at 16:00. Lidia will be speaking, and we'll probably have time for a second speaker if someone would like to be spontaneous. I'm looking for volunteers for the coming weeks, if anyone has something they would like to say, please let me know. Thanks, Norm

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Group meeting 22nd August
by Lidia del Rio 21 Aug '12

21 Aug '12

Dear all, This week's group meeting is on *Wednesday *(tomorrow) at 15:45. Paul Skrzypczyk will talk about tiny thermal engines, and Nikola Ciganovic will present his master thesis. In principle, the meeting is in the usual room (HIT E 41.1). I'll let you know if this changes. Best, Lídia

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Talk by Harry Buhrman: The surprising link between quantum information and functional analysis
by Matthias Christandl 17 Aug '12

17 Aug '12

Dear all, it is a pleasure to announce a second talk (after yesterday's Garden Hose computer demonstration) by Professor Harry Buhrman (CWI Amsterdam), currently visiting professor of the Pauli Center for Theoretical Studies, Institute for Theoretical Physics, ETH Zurich. Date: Friday, 24th of August 2012 Time: 11:00 Location: HIT H42, ETH Hönggerberg Title: The surprising link between quantum information and functional analysis. Abstract: In this talk we will exploit an interesting and surprising connection between questions about multi-party entanglement on one hand and questions about Banach space on the other. In doing so we will solve a 35 year old open problem in Banach space theory. In 1975 Varopoulos asked the question of whether the commutative Banach algebra formed by the p-Schatten space (1 ≤ p≤∞) on the Hilbert space l_2 endowed with the Schur product is a Q-algebra. We resolve this question in the positive. No prior knowledge about Banach space theory is necessary. This is joint work with Jop Briet, Troy Lee, and Thomas Vidick. Looking forward to seeing you, Matthias. Matthias Christandl Institute for Theoretical Physics ETH Zurich http://www.itp.phys.ethz.ch/people/christandl/index

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QSIT Seminar: Haggai Landa, Monday August 20, 2012
by QSIT Seminar 16 Aug '12

16 Aug '12

Dear all Please be informed about the following QSIT Seminar. With best regards, Sandra Künzel ------------------------------------------------------------------------------------------------------ Date: Monday August 20, 2012 Time : 14:00 Place: ETH Science City, HPF G 6 Host: Jonathan Home Beyond the Pseudopotential Approximation Haggai Landa Tel-Aviv University abstract: http://www.nccr-qsit.ethz.ch/news/talks/abstractLanda QSIT Seminar qsit-seminar(a)phys.ethz.ch ETH Zurich Sandra Künzel NCCR QSIT (Finances) HPF E 17 8093 Zurich www.nccr-qsit.ethz.ch

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Group Meeting August 14th
by Normand Beaudry 14 Aug '12

14 Aug '12

Dear all, Tuesday's group meeting will take place at 16:00 in HIT E 41.1. As already announced by Fernando, Itai Arad will be speaking. The details of his talk are below. I won't be there, as I will be away at ICITS. Cheers, Norm Title: A new proof for the 1D area law Abstract: Originating from the works of Bekenstein and Hawking on the entropy of black holes, area laws constitute a central tool for understanding entanglement and locality properties in quantum systems. Essentially, in a system that obeys an area law, the entanglement entropy of a bounded region scales like its boundary area, rather than its volume. In 2007, in a seminal paper, Hastings proved that all 1D quantum spin systems with a constant spectral gap obey an area law in their ground state. The proof was based on the analytical tool of Lieb-Robinson velocity. A major open problem is whether an area law holds also in 2 or more dimensions. In this talk I will present a line of research of the past couple of years culminating in an alternative, entirely combinatorial proof for the 1D area law. The proof uses the Chebyshev polynomial to describe the structure of entanglement in the ground state, yielding an exponentially better bound on the entanglement entropy compared to Hastings bound. Just a slight improvement of our parameters would give a sub-volume law for the 2D case; the combinatorial approach raises hopes that such improvements might be doable. Joint work with A. Kitaev, Z. Landau & U. Vazirani

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Talk by Prof. Harry Buhrman
by Matthias Christandl 10 Aug '12

10 Aug '12

Dear all, it is a pleasure to announce the following talk by Professor Harry Buhrman (CWI Amsterdam), currently visiting professor of the Pauli Center for Theoretical Studies, Institute for Theoretical Physics, ETH Zurich. Date: Thursday, 16th of August 2012 Time: 16:30, cookies &coffee from 16:00 Location: HIT H42, ETH Hönggerberg Title: Position-based cryptography Abstract: Position-based cryptography uses the geographic position of a party as its sole credential. Normally digital keys or biometric features are used. A central building block in position-based cryptography is that of position-verification. The goal is to prove to a set of verifier that one is at a certain geographical location. Protocols typically assume that messages can not travel faster than the speed of light. By responding to a verier in a timely manner one can guarantee that one is within a certain distance of that verifier. Quite recently it was shown that position-verification protocols only based on this relativistic principle can be broken by two attackers who simulate being at a the claimed position while physically residing elsewhere in space. Because of the no-cloning property of quantum information (qubits) it was believed that with the use of quantum messages one could devise protocols that were resistant to such collaborative attacks. Several schemes were proposed that later turned out to be insecure. Finally it was shown that also in the quantum case no unconditionally secure scheme is possible. We will review the field of position-based quantum cryptography and highlight some of the research currently going on in order to develop, using reasonable assumptions on the capabilities of the attackers, protocols that are secure in practice. Looking forward to seeing you, Matthias. Matthias Christandl Institute for Theoretical Physics ETH Zurich http://www.itp.phys.ethz.ch/people/christandl/index

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Itai Arad's talk
by Fernando Brandao 09 Aug '12

09 Aug '12

Hi guys, next Tuesday in the group meeting we will have a talk by Itai Arad who will be visiting throughout the week. Itai will talk about area law. The title and abstract of his talk follow below. Best wishes, Fernando Title: A new proof for the 1D area law Abstract: Originating from the works of Bekenstein and Hawking on the entropy of black holes, area laws constitute a central tool for understanding entanglement and locality properties in quantum systems. Essentially, in a system that obeys an area law, the entanglement entropy of a bounded region scales like its boundary area, rather than its volume. In 2007, in a seminal paper, Hastings proved that all 1D quantum spin systems with a constant spectral gap obey an area law in their ground state. The proof was based on the analytical tool of Lieb-Robinson velocity. A major open problem is whether an area law holds also in 2 or more dimensions. In this talk I will present a line of research of the past couple of years culminating in an alternative, entirely combinatorial proof for the 1D area law. The proof uses the Chebyshev polynomial to describe the structure of entanglement in the ground state, yielding an exponentially better bound on the entanglement entropy compared to Hastings bound. Just a slight improvement of our parameters would give a sub-volume law for the 2D case; the combinatorial approach raises hopes that such improvements might be doable. Joint work with A. Kitaev, Z. Landau & U. Vazirani ___________

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Group Hike: The Juicy Details
by Lidia del Rio 08 Aug '12

08 Aug '12

Dear all, The group hike is already this weekend! We are leaving Zurich on Saturday morning and returning Sunday evening. *We still have some free places! *If you want to join or bring a friend, just write to me. Students, you're invited too! There are four parts to this email: *The Plan:* Timetables and information about activities and places *The Price to Pay: *Cost of each activity, train tickets, and housing. *The Reckless:* List of participants signed up for each activity. Check if your details are correct, and tell me if you want to change them. *The Essentials:* Stuff you should bring, contacts, weather. *The Plan* /Saturday, 11th of August/ 7:20 - we meet at the train station (HB) under the blue lady 7:37 - train to Scuol (2h40) 7:37 - 8:41 Zurich - Landquart (platform 5) 8:49 - 10:16 Landquart - Scuol (platform 6) (since the rafting only starts at 13:15 you may prefer to come later) 10:16 - we drop the bags atChasa Alpina <http://www.chasa-alpina.ch/>, where we will be spending the night This is a big guest house in Scuol. I booked 4 twin rooms with their own bathrooms (priority to couples with babies), and 4 four-bed rooms. Couples with baby (Matthias, Mario) : you can take a mattress from one of the other rooms for the baby. * free time: we can look around, go for a short hike, buy food, and have lunch* 13:15 - *rafting*! (see attached file with details) We are doing the afternoon trip <http://engadin-adventure.ch/index.php/en/afternoon-trips> of Engadin Adventures (alternative plan: the rope course <http://www.seilpark-engadin.ch/index.php/home> (good for children too) or just a hike in the region) *free time: buy food for breakfast, have dinner* If you're only arriving in the evening, we can meet at the restaurant, just call one of us. 19:00 or so - after all that water... relax in the local *spa*! Engadin Bad Scuol <http://www.engadin.com/wellness/baeder/engadin-bad-scuol/?S=1> (trip advisor page <http://www.tripadvisor.com/Attraction_Review-g198845-d645178-Reviews-Engadi…>) Highlight: they have an outdoor swimming pool, aaaaand..... we'll have *shooting stars*! There is a meteor shower <http://stardate.org/nightsky/meteors> (the Perseids) on the night of the 11th. /Sunday, 12th of August/ 8:34 - train and bus (1h) 8:34 - 9:06 train Scuol-Zernez 9:15 - 9:29 bus Zernez station - Zernez, Vallun Chafuol if we miss it, there are connections every hour, at *:34. 9:10 - *hike *in the National Park <http://www.nationalpark.ch/go/en/>! this hike <http://www.wanderland.ch/en/routen_etappen.cfm?subcat=RegionalRoute&id=3174…>, composed of this <http://www.nationalpark.ch/go/en/visit/trails-routes/?trail=9> and this <http://www.nationalpark.ch/go/en/visit/trails-routes/?trail=8> routes in reverse. it's a good 8h hiking. Note: we can also do the hike in reverse, starting from Zernez. The problem with that is that after the hike we'd have to wait for the bus in the valley, and I don't know of any restaurants there. If we choose that, the return bus to Zernez station runs every hour at *:20 and takes 20min (the last one is at 20:20, then 21:50). Evening - train to Zurich (2h30 - 3h) connection 1: 18:24 - 19:37 Zernez-Landquart (platform 8) 19:49 - 20:53 Landquart-Zurich (platform 3) connection 2: 18:49 - 19:00 Zernez - Sagliains 19:03 - 20:10 Sagliains - Landquart (platform 4) 20:19 - 21:23 Landquart - Zurich connection 3: 19:49 - 20:00 Zernez - Sagliains 20:03 - 20:24 Sagliains - Klosters Platz 20:29 - 21:13 Klosters Platz - Landquart 21:19 - 22:23 Landquart - Zurich (platform 4) last connection: 20:47 - 20:57 Zernez - Sagliains 21:03 - 21:24 Sagliains - Klosters Platz 22:29 - 22:13 Klosters Platz - Landquart 22:26 - 23:48 Landquart - Zurich (platform 3) *The Price to Pay* (prices per person, in CHF) Train (with half-tax card) Zurich - Scuol: 31.50 Scuol - Zernez: 6.60 Zernez - Vallun Chafuol: 3.20 Zernez - Zurich: 29.00 Rafting: 110.- (to pay there, in cash or with credit card) Spa: 25.- adults, 16.- children, 5.- infants (under 6 years old) (So says the internet. I didn't confirm it, but there seems to be a 25% discount because the sauna is closed) Accommodation: 45.- in double room, 40.- in 4-bed room add 1.50 of Kurtaxe if you're over 12 years old (pay me, as I will get a payment slip with the total cost) Total: around 250.- per adult, plus food *The Reckless* Rafting: Christian, Cyril + Sarah, Fred, Gilles, Harry + Kees, Johan!, Lea, Lídia, Matthias, Norm, Philippe, Roger Overnight stay, and I guess spa: Anthony, Christian, Cyril + Sarah, Fred, Gilles, Harry + Maria + Kees + Marijne, Johan, Lea, Lídia, Mario Ziman (+ family?), Matthias + Henriette + Georg, Norm, Philippe, Roger Hike: Anthony, Cyril + Sarah, Fred, Gilles, Harry + Maria + Kees + Marijne, Johan, Lea, Lídia, Mario Ziman (+ family?), Norm, Philippe, Roger *The Essentials* Weather: Half-cloudy, 23 °C in Scuol on Saturday, and 22 °C in Zernez on Sunday. The perfect weather for hiking! Contacts: Lídia: 0774215307. Often with no battery/reception/Lídia. Philippe: 0787166515 Renato: 0774550866. Clothing: Swimwear, towel, hat, hiking boots, a jumper, the whole lot. Beauty: Sunscreen, insect repellent (one of either per office), and shampoo (one per office) Electronics: Let's say one [smart phone or camera] per office. And if you have something to watch/photograph stars, that would be amazing. Maps: I have maps for our hike, and little books about the Natural Park. :) Food: Snacks. I'm hoping we can buy the hike food in Scuol. Water bottles: everyone! Do not bring: Bedsheets, laptops, the flu. Wow. I'm super. See you all on Saturday! Lídia

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