Conference

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Why look beyond quantum theory?

Richard Healey University of Arizona
May 30, 2013

PIRSA:13050069
Quantum Fields and Strings
Energy diffusion from relativistic spontaneous localization

Daniel Bedingham Imperial College London
May 30, 2013

PIRSA:13050068
Cosmology
Negativity , Contextuality, Magic and the Power of Quantum Computation

Joseph Emerson Institute for Quantum Computing (IQC)
May 29, 2013

PIRSA:13050084
Quantum Fields and Strings
Path Integrals, Reality and Generalizations of Quantum Theory

Adrian Kent University of Cambridge
May 29, 2013

PIRSA:13050065
Quantum Information

Quantum Foundations
Constraints on generalizations of quantum theory
- Adan Cabello Universidad de Sevilla
- Robert Spekkens Perimeter Institute for Theoretical Physics
- Joseph Emerson Institute for Quantum Computing (IQC)
- Terry Rudolph Imperial College London
- Renato Renner ETH Zurich
May 28, 2013

PIRSA:13050085
Quantum Information

Quantum Fields and Strings
Collapse and Consequences

Philip Pearle Hamilton College
May 28, 2013

PIRSA:13050064
Quantum Fields and Strings
Ontology of collapse theories

Wayne Myrvold Western University

May 28, 2013

PIRSA:13050063
The Quantum-Mechanical Measurement Problem and the Foundations of Statistical Mechanics

David Albert Columbia University
May 28, 2013

PIRSA:13050062
Quantum Foundations
Phenomenology of spontaneous wave-function collapse models

Angelo Bassi University of Trieste
May 27, 2013

PIRSA:13050066
Quantum Fields and Strings
Quantum Mechanics and Spacetime

Bill Unruh University of British Columbia
May 27, 2013

PIRSA:13050060
Quantum Fields and Strings
On the non-extendibility of quantum theory
May 27, 2013

PIRSA:13050059
Quantum Information
Entanglement at strongly-interacting quantum critical points in 2+1D

Roger Melko University of Waterloo
May 10, 2013

PIRSA:13050051
Quantum Information

Why look beyond quantum theory?

Richard Healey University of Arizona
May 30, 2013

PIRSA:13050069
Quantum Fields and Strings
Quantum theory does not define its own landscape. We structure the landscape in response to some contemplated inadequacy of quantum theory. Much foundational work has been motivated by perceived conceptual inadequacies associated with non-locality and the measurement problem. By denying the descriptive function of the quantum state a pragmatist approach may free quantum theory of every conceptual flaw, only to highlight questions we can’t use the theory to address. We should seek to populate the quantum landscape with theories we could use to answer these questions.
Energy diffusion from relativistic spontaneous localization

Daniel Bedingham Imperial College London
May 30, 2013

PIRSA:13050068
Cosmology
We discuss energy diffusion due to spontaneous localization (SL) for a relativistically-fast moving particle. Based on evidence from relativistic extensions of SL we argue that non-relativistic SL should remain valid in the particle rest frame. This implies that calculations can be performed by transforming non relativistic results from the particle rest frame to the frame of the observer. We demonstrate this by considering a relativistic stream of non-interacting particles of cosmological origin and showing how their energy distribution evolves as they traverse the Universe. We present a solution and discuss the potential for astrophysical observations.
Negativity , Contextuality, Magic and the Power of Quantum Computation

Joseph Emerson Institute for Quantum Computing (IQC)
May 29, 2013

PIRSA:13050084
Quantum Fields and Strings
Path Integrals, Reality and Generalizations of Quantum Theory

Adrian Kent University of Cambridge
May 29, 2013

PIRSA:13050065
Quantum Information

Quantum Foundations
I describe some tentative new ideas on modified versions of quantum theory motivated by the path integral formalism, and on other generalizations, and comment on possible experimental implications.
Constraints on generalizations of quantum theory
- Adan Cabello Universidad de Sevilla
- Robert Spekkens Perimeter Institute for Theoretical Physics
- Joseph Emerson Institute for Quantum Computing (IQC)
- Terry Rudolph Imperial College London
- Renato Renner ETH Zurich
May 28, 2013

PIRSA:13050085
Quantum Information

Quantum Fields and Strings
Collapse and Consequences

Philip Pearle Hamilton College
May 28, 2013

PIRSA:13050064
Quantum Fields and Strings
I shall give an introduction to conceptual ideas and equations of the CSL (Continuous Spontaneous Localization) theory of dynamical wave function collapse. Then, I shall discuss various applications of the theory.
Ontology of collapse theories

Wayne Myrvold Western University

May 28, 2013

PIRSA:13050063

The textbook collapse postulate says that, after a measurement, the quantum state of the system on which the measurement was performed , and becomes an eigenstate of the observable measured. Naively, this is what one would expect of dynamical collapse theories. What one gets, instead, is an approximation to such eigenstates. This leaves us with the question of how to interpret such theories as representing a macroscopically definite world. In this talk, I will review some approaches to the ontology of collapse theories, and raise the question: do these yield rival accounts of the nature of the physical world, or are they mere choices of how to hang talk about ordinary objects onto a theory whose physical import is already clear?
The Quantum-Mechanical Measurement Problem and the Foundations of Statistical Mechanics

David Albert Columbia University
May 28, 2013

PIRSA:13050062
Quantum Foundations
Phenomenology of spontaneous wave-function collapse models

Angelo Bassi University of Trieste
May 27, 2013

PIRSA:13050066
Quantum Fields and Strings
Models of spontaneous wave function collapse make predictions, which are different from those of standard quantum mechanics. Indeed, these models can be considered as a rival theory, against which the standard theory can be tested, in pretty much the same way in which parametrized post-Newtonian gravitational theories are rival theories of general relativity. The predictions of collapse models almost coincide with those of standard quantum mechanics at the microscopic level, as these models have to account for the microscopic world, as we know it. Departures become significant when the size of the system increases. However, for larger systems environmental influences become more and more difficult to eliminate. This is the reason why it is tricky to test collapse models experimentally, and so far no decisive test has been performed. We will review the main phenomenological properties of collapse models, in particular the so-called amplification mechanics, as well as the main models, which are debated in the literature (GRW, CSL, QMUPL, DP). We will review the lower bounds on the collapse parameter, and more importantly the upper bounds set by available experimental data. This data come both from experimental tests on earth, and from cosmological observations.
Quantum Mechanics and Spacetime

Bill Unruh University of British Columbia
May 27, 2013

PIRSA:13050060
Quantum Fields and Strings
On the non-extendibility of quantum theory
May 27, 2013

PIRSA:13050059
Quantum Information
I will present a recent theorem that asserts that there cannot exist an "extension of quantum theory" that allows us to make more informative predictions about future measurable events (e.g., whether a horizontally polarized photon passes a polarization filter with a given orientation) than standard quantum theory. The theorem is based on two assumptions about the extended theory: (i) the theory should be compatible with quantum theory (this means, in practice, that the theory is not falsified by current experimental data); (ii) the theory should not preclude experimenters from freely choosing the measurement settings. More precisely, the latter assumption corresponds to the requirement that measurement settings can be chosen at random such that they are independent of any other events, except of course those that lie in the causal future of the choice (i.e., in its future light cone). In addition, I will discuss a corollary of the non-extendibility theorem which leads to the same conclusions as a recent theorem by Pusey, Barrett, and Rudolph on the "reality of the quantum state", based only on the above assumptions.
Entanglement at strongly-interacting quantum critical points in 2+1D

Roger Melko University of Waterloo
May 10, 2013

PIRSA:13050051
Quantum Information
In two or more spatial dimensions, leading-order contributions to the scaling of entanglement entropy typically follow the "area" or boundary law. Although this leading-order scaling is non-universal, at a quantum critical point (QCP), the sub-leading behavior does contain universal physics. Different universal functions can be access through entangling regions of different geometries. For example, for polygonal shaped regions, quantum field theories have demonstrated that the subleading scaling is logarithmic, with a universal coefficient dependent on the number of vertices in the polygon. Although such universal quantities are routinely studied in non-interacting field theories, it often requires numerical simulation to access them in interacting theories. In this talk, I discuss quantum Monte Carlo (QMC) and numerical Linked-Cluster Expansion (NLCE) calculations of the Renyi entropies at the transverse-field Ising model QCP on the 2D square lattice. We calculate the universal coefficient of the vertex-induced logarithmic scaling term, and compare to non-interacting field theory calculations by Casini and Huerta. Also, we examine the shape dependence of the Renyi entropy for finite-size toroidal lattices with smooth boundaries. Such geometries provide a sensitive probe of the gapless wave function in the thermodynamic limit, and give new universal quantities that could be examined by future field-theoretical studies in 2+1D.

Title	Speaker(s)	Date	Talk Type	Info link
Why look beyond quantum theory?	Richard Healey	2013-05-30	Conference	View details
Energy diffusion from relativistic spontaneous localization	Daniel Bedingham	2013-05-30	Conference	View details
Negativity , Contextuality, Magic and the Power of Quantum Computation	Joseph Emerson	2013-05-29	Conference	View details
Path Integrals, Reality and Generalizations of Quantum Theory	Adrian Kent	2013-05-29	Conference	View details
Constraints on generalizations of quantum theory	Adan Cabello, Robert Spekkens, Joseph Emerson, Terry Rudolph, Renato Renner	2013-05-28	Conference	View details
Collapse and Consequences	Philip Pearle	2013-05-28	Conference	View details
Ontology of collapse theories	Wayne Myrvold	2013-05-28	Conference	View details
The Quantum-Mechanical Measurement Problem and the Foundations of Statistical Mechanics	David Albert	2013-05-28	Conference	View details
Phenomenology of spontaneous wave-function collapse models	Angelo Bassi	2013-05-27	Conference	View details
Quantum Mechanics and Spacetime	Bill Unruh	2013-05-27	Conference	View details
On the non-extendibility of quantum theory		2013-05-27	Conference	View details
Entanglement at strongly-interacting quantum critical points in 2+1D	Roger Melko	2013-05-10	Conference	View details

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