Colloquium

Displaying 325 - 336 of 614

Sequential growth dynamics and quantum random walks

David Meyer University of California, San Diego
June 11, 2014

PIRSA:14060042
Mathematical physics
Neutrino Wakes

Ue-Li Pen Canadian Institute for Theoretical Astrophysics (CITA)
June 06, 2014

PIRSA:14060041
Cosmology
How Much Information Can SUSY QM Conserve About SUSY QFT (Part-2)?

S. James Gates Jr. University of Maryland, College Park

June 04, 2014

PIRSA:14060005
Equality

Tobias Fritz Universität Innsbruck

May 21, 2014

PIRSA:14050063
John Paul Robinson: Art, Science and Myth

May 02, 2014

PIRSA:14050062
Quantum thermalization and many-body Anderson localization

David Huse Princeton University
April 30, 2014

PIRSA:14040066
Quantum Foundations
Conformal Standard Model

Krzysztof Meissner University of Warsaw

April 23, 2014

PIRSA:14040061
Exact Classical Simulation of the Quantum-Mechanical GHZ Distribution

Gilles Brassard Université de Montréal
April 16, 2014

PIRSA:14040060
Quantum Information
The computational power of quantum walk

Andrew Childs University of Waterloo

April 11, 2014

PIRSA:14040135
Almost quantum correlations

Antonio Acin Institute of Photonic Sciences (ICFO)

April 09, 2014

PIRSA:14040065
Scribble, Scribble

Isabella Stefanescu

April 02, 2014

PIRSA:14040117
Effective field theory for hydrodynamical systems

Alberto Nicolis Columbia University
March 28, 2014

PIRSA:14030121
Quantum Fields and Strings

Cosmology

Sequential growth dynamics and quantum random walks

David Meyer University of California, San Diego
June 11, 2014

PIRSA:14060042
Mathematical physics
Rideout and Sorkin proposed a classical dynamics for causal sets based upon a sequential growth model. Comparing it with models for sequential growth in other systems, and with the dual goals of generating manifold-like causal sets and finding a quantum dynamics for them, we propose some modifications to their model. The resulting, admittedly speculative, proposal is a type of quantum random walk. We explore its properties in some simple cases.
Neutrino Wakes

Ue-Li Pen Canadian Institute for Theoretical Astrophysics (CITA)
June 06, 2014

PIRSA:14060041
Cosmology
We identify a new non-linear neutrino wake effect, due to the streaming motions of neutrinos relative to dark matter, analogous to the Tseliakhovich-Hirata effect. We compute the effect in moving background perturbation theory, compare to direct n-body simulations, and forecast its observability in current and future surveys. Depending on neutrino mass, this effect could be observable in upcoming surveys through a cross correlation dipole in lensing and galaxies. Unlike previous cosmological neutrino effects, this depends primarily on neutrino mass, making it complementary to measurements that depend on neutrino density.
How Much Information Can SUSY QM Conserve About SUSY QFT (Part-2)?

S. James Gates Jr. University of Maryland, College Park

June 04, 2014

PIRSA:14060005

We provide additional evidence that supersymmetrical quantum mechanical systems can contain a remarkable amount of information about supersymmetrical field
theories in greater than one dimension.
Equality

Tobias Fritz Universität Innsbruck

May 21, 2014

PIRSA:14050063

Equality of two mathematical objects is a seemingly simple and well-understood concept. In this talk, I will do three things to explain why this is a misconception: I will survey different notions of equality, explain how revising the notion of equality has led to an emerging alternative foundation of mathematics called "homotopy type theory", and try to convince you that thinking about equality is relevant to your research in quantum field theory, quantum gravity or quantum foundations.
John Paul Robinson: Art, Science and Myth

May 02, 2014

PIRSA:14050062

Canadian glass artist and Renaissance man, John Paul Robinson, explores the mythic potential of science. Explaining that, “This is the idea that scientific discovery is changing our mythology by changing our understanding of the world and our place in it.” Backed with a firm understanding of the science he references, his sculptures poetically interpret such theoretical phenomena as wave particles, string mathematics and black holes. Most people, especially scientists see mythology and science as mutually exclusive and many believe that a scientific understanding of the world will eventually eliminate the need for myth. This idea is based on a misunderstanding as to what myth really is and it’s relationship to science. Myth is not superstition, fairy tail or lies nor is it truth, history or fact. Myth is Art. Myth is a picture, a story, a map; we use to navigate the world. Not the external material world but the world we all create and hold in our minds. In every human mind is a mythic picture of the world that provides the stage for all we experience. This picture not only helps us navigate our world but also performs the critical function of informing our sense of place and belonging within that world. Science cannot replace myth but it can inform it for mythology deals not with the mysteries generated by our ignorance of how the world works but by our understanding of how the world works. The mathematics of string theory is a powerful tool to describe the world but even physicists have to close their eyes and picture in their minds the world their equations are describing. The equation is pure logic and reason, but the picture of tiny strings playing the music that creates the universe is pure mythology. Award-winning glass artist and instructor John Paul Robinson was educated at the Georgian College of Arts and Technology in Barrie, Ontario, and the Ontario College of Art, where he subsequently taught for a number of years. His work has been exhibited in solo shows throughout Canada and the United States, in cities such as Montreal, Toronto and Chicago. Robinson’s works are held in the collections of The Museum of Civilization in Ottawa, Ontario, the Museum of American Glass in Millville, New Jersey and the Musée des Beaux-arts de Montréal, Québec. He has also created the Amber Archive, an annual participatory art project to communicate our existence and creative endeavours (by artists, designers and scientists) to beings millions of years in the future.
Quantum thermalization and many-body Anderson localization

David Huse Princeton University
April 30, 2014

PIRSA:14040066
Quantum Foundations
Progress in physics and quantum information science motivates much recent study of the behavior of strongly-interacting many-body quantum systems fully isolated from their environment, and thus undergoing unitary time evolution. What does it mean for such a system to go to thermal equilibrium? I will explain the Eigenstate Thermalization Hypothesis (ETH), which posits that each individual exact eigenstate of the system's Hamiltonian is at thermal equilibrium, and which appears to be true for most (but not all) quantum many-body systems. Prominent among the systems that do not obey this hypothesis are quantum systems that are many-body Anderson localized and thus do not constitute a reservoir that can thermalize itself. When the ETH is true, one can do standard statistical mechanics using the `single-eigenstate ensembles', which are the limit of the microcanonical ensemble where the `energy window' contains only a single many-body quantum state. These eigenstate ensembles are more powerful than the traditional statistical mechanical ensembles, in that they can also "see" the quantum phase transition in to the localized phase, as well as a rich new world of phases and phase transitions within the localized phase.
Conformal Standard Model

Krzysztof Meissner University of Warsaw

April 23, 2014

PIRSA:14040061

I will describe a proposal of an enlargement of the Standard Model based on a softly broken conformal symmetry. It contains the usual particles of the SM with right-chiral neutrinos and predicts two new particles: a scalar mixing with the usual Higgs and a naturally weakly coupled axion. I will argue that the Planck scale should be treated as a real physical scale and discuss the hierarchy problem and renormalization from this point of view. I will show that the model does not need any intermediate scales and can be viable up to the Planck scale (in distiction to the Standard Model). I will present experimental predictions of the model.
Exact Classical Simulation of the Quantum-Mechanical GHZ Distribution

Gilles Brassard Université de Montréal
April 16, 2014

PIRSA:14040060
Quantum Information
John Bell has shown that the correlations entailed by quantum mechanics cannot be reproduced by a classical process involving non-communicating parties. But can they be simulated with the help of bounded communication? This problem has been studied for more than twenty years and it is now well understood in the case of bipartite entanglement. However, the issue was still widely open for multipartite entanglement, even for the simplest case, which is the tripartite Greenberger-Horne-Zeilinger (GHZ) state. We give an exact simulation of arbitrary independent von Neumann measurements on general n-partite GHZ states. Our protocol requires O(n^2) bits of expected communication between the parties, and O(n log n) expected time is sufficient to carry it out in parallel. Furthermore, we need only an expectation of O(n) independent unbiased random bits, with no need for the generation of continuous real random variables nor prior shared random variables. In the case of equatorial measurements, we improve earlier results with a protocol that needs only O(n log n) bits of communication and O(log^2 n) parallel time. At the cost of a slight increase in the number of bits communicated, these tasks can be accomplished with a constant expected number of rounds.
The computational power of quantum walk

Andrew Childs University of Waterloo

April 11, 2014

PIRSA:14040135

Quantum computers have the potential to solve certain problems dramatically faster than classical computers. One of the main quantum algorithmic tools is the notion of quantum walk, a quantum mechanical analog of random walk. I will describe quantum algorithms based on this idea, including an optimal algorithm for evaluating Boolean formulas and one of the best known algorithms for simulating quantum dynamics. I will also show how quantum walk can be viewed as a universal model of quantum computation.
Almost quantum correlations

Antonio Acin Institute of Photonic Sciences (ICFO)

April 09, 2014

PIRSA:14040065

Quantum theory is successfully tested in any experimental lab every day. Apart from its experimental validity, quantum theory also constitutes a robust theoretical framework: small variations of its formalism often lead to highly implausible consequences, such as violation of the no-signalling principle or a significant increase of the computational power. In fact, it has been argued that quantum theory may represent an island in theory space. We show that, at the level of correlations, quantum theory may not be as special as initially thought. In order to do so, we define the set of almost quantum correlations and prove that this set is (i) strictly larger than the set of quantum correlations but (ii) satisfies most of the information principles introduced to characterize quantum correlations, such as local orthogonality, macroscopic locality, no advantage for nonlocal computation or non-trivial communication complexity. We also provide numerical evidence that the set is compatible with information causality. Finally, we briefly discuss how the set of almost quantum correlations naturally emerges in the consistent histories approach to quantum physics.
Scribble, Scribble

Isabella Stefanescu

April 02, 2014

PIRSA:14040117

The live performance of a drawing contains information, expression and meaning that a finished drawing does not. Part performance, part demonstration, Isabella Stefanescu’s talk will explore the artistic challenges in creating performance pieces with the Euphonopen, an assemblage of hardware and software designed to map the characteristic mark making gestures of an artist to sound. Various stages of the Euphonopen project have been presented at SIGGRAPH (2010), Concordia University Live Electroacoustic Colloquium (2011), McGill University Time Forms Conference (2013).
Effective field theory for hydrodynamical systems

Alberto Nicolis Columbia University
March 28, 2014

PIRSA:14030121
Quantum Fields and Strings

Cosmology
I will review a recently proposed formalism that describes fluids and superfluids in effective field theory terms. I will then focus on applying this formalism to peculiar string-like objects that exist in fluid systems: vortex lines and vortex rings. These do not obey Newton's second law, and, as a consequence, their behavior is highly counterintuitive. I will describe how effective field theory provides us with an optimal tool to understand how they move and how they interact with one another and with sound.

Title	Speaker(s)	Date	Talk Type	Info
Sequential growth dynamics and quantum random walks	David Meyer	2014-06-11	Scientific Series	View details
Neutrino Wakes	Ue-Li Pen	2014-06-06	Scientific Series	View details
How Much Information Can SUSY QM Conserve About SUSY QFT (Part-2)?	S. James Gates Jr.	2014-06-04	Scientific Series	View details
Equality	Tobias Fritz	2014-05-21	Scientific Series	View details
John Paul Robinson: Art, Science and Myth		2014-05-02	Scientific Series	View details
Quantum thermalization and many-body Anderson localization	David Huse	2014-04-30	Scientific Series	View details
Conformal Standard Model	Krzysztof Meissner	2014-04-23	Scientific Series	View details
Exact Classical Simulation of the Quantum-Mechanical GHZ Distribution	Gilles Brassard	2014-04-16	Scientific Series	View details
The computational power of quantum walk	Andrew Childs	2014-04-11	Scientific Series	View details
Almost quantum correlations	Antonio Acin	2014-04-09	Scientific Series	View details
Scribble, Scribble	Isabella Stefanescu	2014-04-02	Scientific Series	View details
Effective field theory for hydrodynamical systems	Alberto Nicolis	2014-03-28	Scientific Series	View details

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