Conceptual questions in statistical physics

**Conceptual questions in statistical physics**

# 22 October 2008

#### Ecole Normale Supérieure, Salle Weill,

entrée au 45 rue d'Ulm, Paris 5ème

#### Programme

9:30 *Alexei Grinbaum *(CEA-Saclay). Welcome remarks
9:45 *Jos Uffink* (University of Utrecht). On the analogy between thermodynamics and quantum entanglement

11:00 Chris Timpson (Oxford University). Thinking about information in the classical and quantum worlds

14:30 Tony Short (University of Cambridge). A quantum approach to thermal equilibrium

15:45 *Owen Maroney* (University of Sydney). Justifying Landauer's Principle

17:00 Discussion

#### Abstracts

**Jos Uffink (University**** of Utrecht)**

**“On the analogy between thermodynamics and quantum entanglement”**

According to the second law of thermodynamics the entropy of a system cannot decrease by adiabatic state transformations. In quantum mechanics, the "degree of entanglement" of a state cannot increase under state transformations of a certain kind (local operations assisted by classical communication) In this talk I will explore the significance of the analogy between these two statements.

**Chris Timpson (Oxford University****)**

**“Thinking about information in the classical and quantum worlds”**

Information plays, or is said to play, an increasingly central role in our thinking about the world; an increasingly central role in our thinking about physics. But what exactly *is* information? In this talk I will review some ways of answering this question; and reflect on the similarities and differences between information in the quantum world and in the classical. We need to get off on the right foot at the beginning in our analysis of the concept of information if we are to make any progress in the deeper question of what role a concept like information has to play in fundamental physics. I will suggest what that right foot is; and make a few steps.

**Tony Short (****University**** of ****Cambridge****)**

**“A quantum approach to thermal equilibrium”**

One of the biggest challenges in understanding statistical mechanics is its use of probabilities, which seem to reflect our own ignorance rather

than anything physical. Here, I will describe a relatively recent alternative, in which probabilities arise as a natural and objective consequence of quantum theory. In this context, I will show that reaching equilibrium is an almost univeral quantum phenomenon.

**Owen Maroney (University of Sydney****)**

**“Justifying Landauer's Principle”**

A critical review of the attempts to provide sound theoretical justification of Landauer's Principle, what is being justified, and what are the problems.

#1076 - Last update : 09/19 2008