Hi everyone,
today we'll meet in K51 at our new time, 15:45. We have a guest from
downtown, Tobias Sutter, who will tell us something interesting about
optimization problems.
Best,
-joe
Hi all,
tomorrow we'll hear from Nuriya Nurgalieva on her master's thesis. The
title and abstract follow. We should also discuss whether Monday at
4pm will be a convenient meeting time for everyone this semester.
Best,
-joe
Title: Quantum reference frames for experiments where observers can be measured
Abstract: Frauchiger and Renner recently proposed an expansion of
Wigner’s friend experiment to prove that single-world interpretations
of quantum theory cannot be self-consistent. …
[View More]Experimenters are modeled
as agents who use quantum theory, and additionally can themselves be
measured as physical systems. However, Frauchiger and Renner’s
description of the experiment implicitly assumes that all agents have
access to perfect, classical reference frames. In doing so it imposes
artificial classicality on a setting that tries to model only quantum
evolutions, and risks missing out on subtleties that could explain the
paradox. We model each lab as a system which consists of a spin, a
reference frame and an agent’s memory, evolving under a unitary.
Concretely, we investigate whether different agents refer to the same
degrees of freedom and quantum subsystems when they talk about the
outcome of a measurement. Our results show that in the setting with
the finite reference frames agents are not able to make deterministic
predictions.
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Hi all,
tomorrow we'll have yesterday's group meeting --- Henrik Wilming from
FU Berlin will give a talk at 4pm in H51. Title and abstract below.
Best,
-joe
Statistical ensembles without typicality
-----------------------------------------
Maximum-entropy ensembles are key primitives in statistical mechanics
from which thermodynamic properties can be derived. Over the decades,
several approaches have been put forward in order to justify from
minimal assumptions the use of these ensembles in …
[View More]statistical
descriptions. I will explain a new approach to derive maximum-entropy
ensembles taking a strictly operational perspective. To do that I will
consider the set of possible transitions that a system can undergo
together with an environment, when one only has partial information
about the quantum states of both the system and its environment. The set
of all these allowed transitions encodes thermodynamic laws and
limitations on thermodynamic tasks as particular cases. Our main result
is that the set of allowed transitions coincides with the one possible
if both system and environment were assigned the maximum entropy state
compatible with the partial information. This provides a new explanation
for the overwhelming success of such ensembles and provides a derivation
without relying on considerations of typicality or information-theoretic
measures.
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Dear all,
I'm giving a tutorial talk at QCRYPT next week, "Composability in Quantum
Cryptography". For those who won't be at QCRYPT, you can listen to same
talk the day after tomorrow:
Date/Time: 14 September 2017, 10.15am
Duration: 80 minutes
Location: CAB H53 (Zentrum)
Title: Composability in Quantum Cryptography
Abstract:
This is (hopefully) a very accessible introduction on how to define
composable security, with many examples from quantum key distribution,
encryption, authentication, …
[View More]device-independent cryptography, and baking
bread.
Best,
Christopher
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Hi all,
tomorrow Vilasini will give a tutorial-style talk on quantum
causality. My sending this message is purely a matter of
correlation... ;)
Best,
-joe