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.

 

Tuesday Feb 26, 2013
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Tuesday Feb 05, 2013
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The general boundary formulation (GBF) is an atemporal, but spacetime local formulation of quantum theory. Usually it is presented in terms of the amplitude formalism, which, in the presence of a background time, recovers the pure state formalism of the standard formulation of quantum theory. After reviewing the essentials of the amplitude formalism I will introduce a new "positive formalism", which recovers instead a mixed state formalism.

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Tuesday Dec 11, 2012
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Quantum chaos is the study
of quantum systems whose classical description is chaotic.

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Tuesday Nov 20, 2012
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In
a generic quantum experiment we have a given set of devices analyzing some
physical property of a system. To each device involved in the experiment we
associate a set of random outcomes corresponding to the possible values of the
variable analyzed by the device. Devices have apertures that permit physical
systems to pass through them. Each aperture is labelled as "input" or
"output" depending on whether it is assumed that the aperture lets
the system go inside or outside the device. Assuming a particular input/output

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Tuesday Nov 13, 2012
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Negativity in a quasi-probability representation is typically
interpreted as an indication of nonclassical behavior. 

However, this does not preclude bases that are non-negative from
having interesting applications---the single-qubit

stabilizer states have non-negative Wigner functions and yet
play a fundamental role in many quantum information tasks.

We determine what other sets of quantum states and measurements
of a qubit can be non-negative in a quasiprobability

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Tuesday Nov 06, 2012
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If probabilities represent knowledge, what is an "unknown

probability"? De Finetti's theorem licenses the view that it is simply a

convenient metaphor for a certain class of knowledge about a series of

events. There are quantum versions for "unknown states" and
"unknown

channels". I will explain how "unknown measurements" can be
rehabilitated

too.



I will then move to a totally different topic. The Bloch sphere is handy

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Thursday Nov 01, 2012
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The fact that the quantum wavefunction of a many-particle system is a function on a high-dimensional configuration space, rather than on spacetime, has led some to suggest that any realist understanding of quantum mechanics must regard configuration space as more fundamental than spacetime. Worse, it seems that a wavefunction monist ontology cannot help itself to talk of "configuration space" at all, without particles for the configurations to be configurations of.

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Tuesday Oct 23, 2012
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I will discuss the central role of correlations in
thermodynamic directionality, how strong correlations can distort the
thermodynamic arrow and contrast these distortions in both the classical and
quantum regimes. These distortions constitute non-linear entanglement witnesses,
and give rise to a rich information-theoretic structure. I shall explain how
these results are then cast into the language of fluctuation theorems to derive
a generalized exchange fluctuation theorem, and discuss the limitations of such
a framework.

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