Soumis par Anonymous le Juin 26, 2013 - 9:10am

Physical theories ought to be built up from colloquial notions such as ’long bodies’, ’energetic sources’ etc. in terms of which one can define pre-theoretic ordering relations such as ’longer than’, ’more energetic than’. One of the questions addressed in previous work is how to make the transition from these pre-theoretic notions to quantification, such as making the transition from the ordering relation of ’longer than’ (if one body covers the other) to the notion of how much longer.

Soumis par Anonymous le Juin 25, 2013 - 9:29am

Weak values were introduced by Aharonov, Albert, and Vaidman 25 years ago, but it is only in the last 10 years that they have begun to enter into mainstream physics. I will introduce weak values as done by AAV, but then give them a modern definition in terms of generalized measurements. I will discuss their properties and their uses in experiment. Finally I will talk about what they have to contribute to quantum foundations.

Soumis par Anonymous le Juin 3, 2013 - 9:16am

I argue that quantum mechanics cannot usefully be extended to a theory of the whole universe, so the task of quantum foundations is to discover that cosmological theory which reduces to quantum mechanics when restricted to small subsystems of the universe. I argue that that cosmological theory will be based on a global notion of physical time which implies the distinction between past, present and future is real and objective. These motivate two examples of novel formulations of quantum theory: the real ensemble formulation and the principle of precedence. Each may imply departure

Soumis par Anonymous le Juin 3, 2013 - 9:16am

Characterising quantum non-locality using simple physical principles has become a hot topic in quantum foundations of late. In the simpler case of local hidden variable models, the space of allowed correlations can be characterised by requiring that there exists a joint probability distribution over all possible experimental outcomes, from which the experimental probabilities arise as marginals. This follows from Bell’s causality condition. But the existing characterisations of quantum correlations are far from being so straightforward.

Soumis par Anonymous le Mai 29, 2013 - 9:47am

Soumis par Anonymous le Mai 22, 2013 - 12:00pm

The process of canonical quantization:is reexamined with the goal of

ensuring there is only one reality, where $\hbar>0$, in which classical

and quantum theories coexist. Two results are a clarification of the effect of

canonical coordinate transformations and the role of Cartesian coordinates.

Other results provide validation

Soumis par Anonymous le Mai 6, 2013 - 8:57am

The Pauli exclusion principle is a constraint on the

natural occupation numbers of fermionic states. It has been suspected for

decades, and only proved very recently, that there is a multitude of further

constraints on these numbers, generalizing the Pauli principle. Surprisingly,

these constraints are linear: they cut out a geometric object known as a

polytope. This is a beautiful mathematical result, but are there systems whose

physics is governed by these constraints?

Soumis par Anonymous le Mai 1, 2013 - 8:57am

The Wigner-Araki-Yanase (WAY) theorem delineates

circumstances under which a class of quantum measurements is ruled out.

Specifically, it states that any observable (given as a self adjoint operator)

not commuting with an additive conserved quantity of a quantum system and

measuring apparatus combined admits no repeatable measurements. I'll review the

content of this theorem and present some new work which generalises and

strengthens the existing results.

Soumis par Anonymous le Avril 30, 2013 - 8:30am

A recent development in

information theory is the generalisation of quantum Shannon information theory

to the operationally motivated smooth entropy information theory, which

originates in quantum cryptography research. In a series of papers the first

steps have been taken towards creating a statistical mechanics based on smooth

entropy information theory. This approach turns out to allow us to answer

questions one might not have thought were possible in statistical mechanics,