July 2018 - ITP-quantumseminare - lists.phys.ethz.ch

today's meeting E41.1 @ 15:30
by Joe Renes 30 Jul '18

30 Jul '18

Hi all, today we'll hear from Nick Spooner, another member of the group of Alessandro Chiesa in Berkeley who is visiting the CS department. His talk is titled "Spatial Isolation Implies Zero Knowledge Even in a Quantum World". See https://eccc.weizmann.ac.il/report/2018/044/ or the google calendar for more details. Best, -joe

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No meeting today
by Joe Renes 23 Jul '18

23 Jul '18

Hi all, No meeting today as several of us out of town this week. We'll have a full report from the Beyond IID conference next week! Best, -joe

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today's seminar E41.1 @ 3:30 pm
by Joe Renes 16 Jul '18

16 Jul '18

Hi all, today I'll say a few things about a "Double-edged factor graphs", which are a nice graphical representation of quantum states/channels/measurements/etc that generalize a representation of probabilities called factor graphs (which are widely used in classical error-correction). Best, -joe

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no meeting today
by Joe Renes 09 Jul '18

09 Jul '18

Hi all, today's meeting is cancelled, but see the following announcement. Best, -joe ------- Igor Sokolov (IBM Zurich and ITP) will talk about Quantum algorithms for electronic structure calculations Date: Monday, July 9 Time: 13:30 Place: HIT K 51

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Talk today: Laura Burri 4pm, Irchel Y36K08  , Tensor product factorizations and locality
by Lidia del Rio 06 Jul '18

06 Jul '18

Dear all, Laura Burri's bachelor thesis presentation will take place today at 4:00pm in the UZH Irchel campus, room Y36K08  . It will be a 25min talk followed by questions. Title and abstract below. Hilbert space factorisation and locality  In quantum mechanics, the tensor product rule allows one to describe independent systems jointly. However, if one is given a global system, there is a priori no reason for considering some factorization of the system’s state space as “the only physical one”. Thus, if multiple agents observe the same system, their implicit assumptions on how the state space factors do not necessarily coincide. Is it possible to derive from the agents’ perspectives how their implicitly assumed factorizations are related? The problem of answering this question is what we call The Factorization Problem as it pays attention to the various possible factorizations of the same Hilbert space. The aim of solving the factorization problem is to derive from agents’ abilities how their objects of observation are related, rather than assume from the outset knowledge about this relation. In this work I motivate and define the factorization problem. Furthermore, I introduce a classification of how two agents’ assumptions about the factorization of some system’s state space can be related. For some of these classes, conditions have been found which are fundamental for solving the factorization problem. Yet, no generic solution of the factorization problem exists. Best, Lídia

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today's meeting E41.1 @ 15:30
by Joe Renes 02 Jul '18

02 Jul '18

Hi all, today we have a guest speaker, Peter Manohar from Berkeley. He'll talk about "Testing linearity against non-signaling strategies". The paper is available at http://drops.dagstuhl.de/opus/volltexte/2018/8873/ (I think), and the abstract is below. Best, -joe Abstract: Non-signaling strategies are collections of distributions with certain non-local correlations. They have been studied in Physics as a strict generalization of quantum strategies to understand the power and limitations of Nature's apparent non-locality. Recently, they have received attention in Theoretical Computer Science due to connections to Complexity and Cryptography. We initiate the study of Property Testing against non-signaling strategies, focusing first on the classical problem of linearity testing (Blum, Luby, and Rubinfeld; JCSS 1993). We prove that any non-signaling strategy that passes the linearity test with high probability must be close to a quasi-distribution over linear functions. Quasi-distributions generalize the notion of probability distributions over global objects (such as functions) by allowing negative probabilities, while at the same time requiring that "local views" follow standard distributions (with non-negative probabilities). Quasi-distributions arise naturally in the study of Quantum Mechanics as a tool to describe various non-local phenomena. Our analysis of the linearity test relies on Fourier analytic techniques applied to quasi-distributions. Along the way, we also establish general equivalences between non-signaling strategies and quasi-distributions, which we believe will provide a useful perspective on the study of Property Testing against non-signaling strategies beyond linearity testing.

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