Quantum Foundations

This series consists of talks in the area of Foundations of Quantum Theory. Seminar and group meetings will alternate.

Seminar Series Events/Videos

Currently there are no upcoming talks in this series.

A First-Principles Implementation of Scale Invariance Using Best Matching

Tuesday Sep 15, 2009
Speaker(s):

We present a first-principles implementation of {\em spatial} scale invariance as a local gauge symmetry in geometry dynamics using the method of best matching. In addition to the 3-metric, the proposed scale invariant theory also contains a 3-vector potential A_k as a dynamical variable. Although some of the mathematics is similar to Weyl's ingenious, but physically questionable, theory, the equations of motion of this new theory are second order in time-derivatives. It is tempting to try to interpret the vector potential A_k as the electromagnetic field.

Collection/Series:
Scientific Areas:

Betting on Quantum Theory

Tuesday Sep 08, 2009

Betting (or gambling) is a useful tool for studying decision-making in the face of [classical] uncertainty. We would like to understand how a quantum "agent" would act when faced with uncertainty about its [quantum] environment. I will present a preliminary construction of a theory of quantum gambling, motivated by roulette and quantum optics. I'll begin by reviewing classical gambling and the Kelly Criterion for optimal betting. Then I'll demonstrate a quantum optical version of roulette, and discuss some of the challenges and pitfalls in designing such analogues.

Collection/Series:
Scientific Areas:

Entanglement detection with bounded reference frames

Tuesday Aug 04, 2009
Speaker(s):

Violation of local realism can be probed by theory–independent tests, such as Bell’s inequality experiments. There, a common assumption is the existence of perfect, classical, reference frames, which allow for the specification of measurement settings with arbitrary precision. However, if the reference frames are bounded'', only limited precision can be attained. We expect then that the finiteness of the reference frames limits the observability of genuine quantum features.

Collection/Series:
Scientific Areas:

Classical fields as the natural ontic structure for quantum theory

Tuesday Jun 16, 2009
Speaker(s):

Although most realistic approaches to quantum theory are based on classical particles, QFT reveals that classical fields are a much closer analog. And unlike quantum fields, classical fields can be extrapolated to curved spacetime without conceptual difficulty. These facts make it tempting to reconsider whether quantum theory might be reformulated on an underlying classical field structure.

Collection/Series:
Scientific Areas:

Quantum foundations minus probability theory

Tuesday May 05, 2009
Speaker(s):

Researchers in quantum foundations claim (D'Ariano, Fuchs, ...):

Quantum = probability theory + x

and hence:

x = Quantum - probability theory

Guided by the metaphorical analogy:

probability theory / x = flesh / bones

we introduce a notion of quantum measurement within x, which, when flesing it with Hilbert spaces, provides orthodox quantum mechanical probability calculus.

Collection/Series:
Scientific Areas:

Inference and Questions

Tuesday Mar 31, 2009
Speaker(s):

We know the mathematical laws of quantum mechanics, but as yet we are not so sure why those laws should be inevitable. In the simpler but related environment of classical inference, we also know the laws (of probability). With better understanding of quantum mechanics as the eventual goal, Kevin Knuth and I have been probing the foundations of inference. The world we wish to infer is a partially-ordered set ('poset') of states, which may as often supposed be exclusive, but need not be (e.g. A might be a requirement for B).

Collection/Series:
Scientific Areas:

The Effectiveness of Group Theory in Quantum Mechanics

Thursday Mar 12, 2009
Speaker(s):

Eugene Wigner and Hermann Weyl led the way in applying the theory of group representations to the newly formulated theory of quantum mechanics starting in 1927. My talk will focus, first, on two aspects of this early work. Physicists had long exploited symmetries as a way of simplifying problems within classical physics.

Collection/Series:

What is the objective face of a die?

Tuesday Mar 10, 2009
Speaker(s):

Quantum foundations in the light of gauge theories We will present the conjecture according to which the fact that q and p cannot be both observables'' of the same quantum system indicates that there is a remnant universal symmetry acting on classical states. In order to unpack this claim we will generalize to unconstrained systems the gauge correspondence between properties defined by first-class constraints and gauge symmetries generated by these constraints.

Collection/Series:
Scientific Areas:

Entanglement and measurement in general probabilistic theories

Tuesday Mar 03, 2009
Speaker(s):

Quantum mechanics is a non-classical probability theory, but hardly the most general one imaginable: any compact convex set can serve as the state space for an abstract probabilistic model (classical models corresponding to simplices). From this altitude, one sees that many phenomena commonly regarded as characteristically quantum' are in fact generically non-classical'. In this talk, I'll show that almost any non-classical probabilistic theory shares with quantum mechanics a notion of entanglement and, with this, a version of the so-called measurement problem.

Collection/Series:
Scientific Areas:

deBroglie-Bohm and the Timeless Mechanics of Jacobi

Tuesday Feb 10, 2009
Speaker(s):

A standard canonical quantization of general relativity yields a time-independent Schroedinger equation whose solutions are static wavefunctions on configuration space. Naively this is in contradiction with the real world where things do change. Broadly speaking, the problem how to reconcile a theory which contains no concept of time with a changing world is called 'the problem of time'.

Collection/Series:
Scientific Areas:

RECENT PUBLIC LECTURE

Quantum Entanglement and Superconductivity

Speaker: Subir Sachdev