Date: Sep 27, 2016
Title: Statistics, Quantum Information and Gravity
Remarks: Venue: Lecture Hall (1F), Kavli IPMU

9:00 - 10:00 Masanao Ozawa (Nagoya U)
10:00 - 10:30 Coffee Break
10:30 - 11:30 Yasuyuki Kawahigashi (U Tokyo)
11:30 - 13:00 Lunch
13:00 - 14:00 Hal Tasaki (Gakushuin U)
14:00 - 15:00 Takahiro Sagawa (U Tokyo)
15:00 - 16:00 Tea Time
16:00 - 17:00 Simeon Hellerman (Kavli IPMU)

Hirosi Ooguri

Title and Abstract:
Masanao Ozawa (Nagoya University)
<Title>: Quantum measurement theory for quantum fields
<Abstract>: It is well established that quantum measurements are characterized by so-called quantum instruments, or normalized completely positive map valued measures, for quantum systems with finite degrees of freedom. We review some implications of this theory in quantum information, and then we discuss the problem of extending quantum measurement theory to quantum fields. We present our recent result showing that local quantum measurements are characterized by quantum instruments on local algebras in the framework of algebraic quantum field theory under moderate assumptions.

Yasuyuki Kawahigashi (University of Tokyo)
<Title>: Conformal field theory and operator algebras
<Abstract>: We present the operator algebraic framework to study 2-dimensional conformal field theory. We emphasize representation theoretic aspects of chiral conformal field theory, and describe a recently established connection with vertex operator algebras. We also briefly explain superconformal field theory, full conformal field theory and boundary conformal field theory.

Hal Tasaki (Gakushuin University)
<Title>: What is thermal equilibrium and how do we get there?
<Abstract>: We discuss the foundation of equilibrium statistical mechanics within isolated macroscopic quantum systems. We shall characterize thermal equilibrium based on "typicality" picture and large-deviation type consideration. We then present a simple (and hopefully realistic) condition based on the notion of effective dimension which guarantees that a nonequilibrium initial state evolves into the thermal equilibrium. We also discuss preliminary results about the time scale required for thermalization.

Takahiro Sagawa (University of Tokyo)
<Title>: Thermodynamics of information in quantum many-body systems
<Abstract>: We discuss a fundamental aspect of the relationship between information and thermodynamics. I will first discuss the concepts of thermodynamic entropy and information entropy, and review the role of information in the second law of thermodynamics. I will then present our recent result on the second law and the fluctuation theorem with information entropy for quantum many-body systems that are in quantum pure states, and discuss how thermal fluctuations emerge from purely quantum fluctuations.

Simeon Hellerman (Kavli IPMU)
<Title>: Quantum Information Theory Of The Gravitational Anomaly
<Abstract>: Recent papers have appeared describing certain peculiarities of measures of quantum-mechanical entanglement in local quantum field theories with nonvanishing gravitational anomaly. We show that these peculiarities follow from the fact that the Hilbert space of a gravitationally anomalous QFT simply does not ever tensor factorize at all into Hilbert spaces in complementary regions, and thus the defining assumption on which the concept of quantum entanglement is based, always fails in gravitationally anomalous theories. We show the breakdown of all known definitions of entanglement when the gravitationally anomaly is present, and give a general proof that no such definition exists, based on a series of tight logical connections between tensor factorizations, boundary conditions, and the gravitational anomaly. We discuss the implications for holographic AdS_3 theories with gravitationally anomalous CFT_2 dual, such as topologically massive gravity.