Search Talks

Search results from PIRSA

10249 - 10260 of 16716 Results

Time, cosmology and quantum foundations

Lee Smolin Perimeter Institute for Theoretical Physics
May 31, 2013

PIRSA:13050072
Quantum Physics

Astrophysics
Towards a realist's interpretation of the path integral

Petros Wallden University of Athens

May 31, 2013

PIRSA:13050071
Generalizations of Quantum Theory
- Lucien Hardy Perimeter Institute for Theoretical Physics
- Rafael Sorkin Perimeter Institute for Theoretical Physics
- Wayne Myrvold Western University
- Howard Barnum University of New Mexico
- Joe Henson BNP Paribas Asset Management London
- Markus Müller Institute for Quantum Optics and Quantum Information (IQOQI) - Vienna
May 30, 2013

PIRSA:13050081
Quantum Physics

High Energy Physics
CDT without preferred foliation

Samo Jordan Utrecht University
May 30, 2013

PIRSA:13050082
General Relativity & Quantum Cosmology
Conjugates, Correlation and the Jordan Structure of Finite-Dimensional Quantum Theory
May 30, 2013

PIRSA:13050070
Mathematical Physics
Why look beyond quantum theory?

Richard Healey University of Arizona
May 30, 2013

PIRSA:13050069
High Energy Physics
Fuzzballs to Firewalls: A Post-Firewall Review of the Fuzzball Proposal: Lecture 1

Steve Avery Institute of Mathematical Sciences
May 30, 2013

PIRSA:13050087
High Energy Physics
Energy diffusion from relativistic spontaneous localization

Daniel Bedingham Imperial College London
May 30, 2013

PIRSA:13050068
Astrophysics
Nanoparticle interferometry: experimental tests of the quantum superposition principle at high mass and complexity.

Markus Arndt Technische Universität Wien

May 29, 2013

PIRSA:13050067
Negativity , Contextuality, Magic and the Power of Quantum Computation

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

PIRSA:13050084
High Energy Physics
Path Integrals, Reality and Generalizations of Quantum Theory

Adrian Kent University of Cambridge
May 29, 2013

PIRSA:13050065
Quantum Physics

Quantum Physics
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 Physics

High Energy Physics

Time, cosmology and quantum foundations

Lee Smolin Perimeter Institute for Theoretical Physics
May 31, 2013

PIRSA:13050072
Quantum Physics

Astrophysics
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 departures from the expected quantum evolution for sufficiently large and complex quantum systems.
Towards a realist's interpretation of the path integral

Petros Wallden University of Athens

May 31, 2013

PIRSA:13050071

Having a fundamental spacetime view of physics, appears more justified in attempting to construct a quantum theory of gravity. In this talk, motivated by the latter, a path integral approach is adopted and an attempt to construct a self-consistent realistic histories formulation of quantum theory is presented. After revising the histories viewpoint of classical physics, the quantum case is considered. However, the nature of the probabilities arising from the path integral, leads us to alter the classical picture. The new ontology is that of a coevent (or a coarse grained history), and we analyse the consequences of this (relatively) novel proposal.
Generalizations of Quantum Theory
- Lucien Hardy Perimeter Institute for Theoretical Physics
- Rafael Sorkin Perimeter Institute for Theoretical Physics
- Wayne Myrvold Western University
- Howard Barnum University of New Mexico
- Joe Henson BNP Paribas Asset Management London
- Markus Müller Institute for Quantum Optics and Quantum Information (IQOQI) - Vienna
May 30, 2013

PIRSA:13050081
Quantum Physics

High Energy Physics
CDT without preferred foliation

Samo Jordan Utrecht University
May 30, 2013

PIRSA:13050082
General Relativity & Quantum Cosmology
Causal dynamical triangulations (CDT) define a nonperturbative path integral for quantum gravity as a sum over triangulations. Causality is enforced on the kinematical level by means of a preferred
foliation.

In this talk I present a new model of dynamical triangulations based on Lorentzian building blocks, where the triangulations in general do not have such a preferred foliation. The essential ingredients of the new model are a local causality constraint and a consistency condition on the global flow of time. After a compact review on CDT I discuss the theoretical aspects of the new model in 1+1 and 2+1 dimensions, followed by a presentation of numerical results in 2+1 dimensions. These results show that the new model and CDT have similar long-distance properties in 2+1 dimensions.
Conjugates, Correlation and the Jordan Structure of Finite-Dimensional Quantum Theory
May 30, 2013

PIRSA:13050070
Mathematical Physics
The last few years have seen a spate of operational or information-theoretic
derivations (or \reconstructions") of nite-dimensional quantum mechanics [1]. These rest of some strong assumptions. In particular, most assume the state of a composite system is entirely determined by the joint probabilities it assigns to the outcomes of measurements on the component systems. This condition, often called local tomography, is satis ed by neither real nor quaternionic quantum theory. If we are interested in the possibilities for theories more general than orthodox quantum mechanics, we might wish to relax this constraint.
In this talk I will discuss a weaker system of assumptions, involving correla-
tions between a probabilistic system and an isomorphic conjugate system, that leads to a representation of such systems in terms of euclidean Jordan algebras [2]. These have a well-known classi cation as direct sums of real, complex or quaternionic quantum systems, possibly the exceptional Jordan algebra, and spin factors. The last are a form of \bit", characterized by a family of two-valued observables, parametrized by antipodal vectors in a sphere of arbitrary dimension. Orthodox quantum mechanics can be singled out by imposing local tomography, plus the existence of a qubit as additional axioms [3]. However, there is a natural way to form non-signaling, but generally non-locally tomo-graphic, composites of systems based on special euclidean Jordan algebras (that is, excluding the exceptional one). This yields a probabilistic theory strictly, but not wildly, more general than orthodox nite-dimensional QM; one that elegantly uni es real, complex and quaternionic quantum theory, has a simple operational basis, and allows for a spectrum of bits more general than permitted in orthodox quantum theory. Parts of this talk reflect ongoing joint work with Howard Barnum, Matthew Graydon and Cozmin Ududec.
References:
[1] G. Chiribella, M. D'Ariano and P. Perinotti, Phys. Rev. A 84, (2011), 012311-
012350; B. Dakic and C. Brukner, in H. Halvorson (ed.), Deep Beauty, Cambridge,
2011; P. Goyal, Phys. Rev. A 78 (2008), 052120-052146; L. Hardy, arXiv:quant-
ph/0101012 (2001); L. Masanes and M. Mueller, New J. Phys. 13 (2011) ; J. Rau,
Annals of Physics 324 (2009) 2622{2637;
[2] A. Wilce, Conjugates, correlation and quantum mechanics, arXiv:1206.2897 (2012)
[3] H. Barnum and A. Wilce, Local tomography and the Jordan structure of quantum
theory, arXiv:1202.4513, (2012)
Why look beyond quantum theory?

Richard Healey University of Arizona
May 30, 2013

PIRSA:13050069
High Energy Physics
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.
Fuzzballs to Firewalls: A Post-Firewall Review of the Fuzzball Proposal: Lecture 1

Steve Avery Institute of Mathematical Sciences
May 30, 2013

PIRSA:13050087
High Energy Physics
The fuzzball proposal makes a conjecture about the nature of black hole
microstates. Now, more than a decade old and including several different
philosophies and perspectives, it is especially relevant after the recent
firewall argument and ensuing debate. Over three lectures, I plan to start
with a very general discussion of the general ideas and motivations, then
review the theoretical evidence from string theory, and finally close by
discussing open questions, including the fate of a freely falling observer

as he/she passes through the black hole horizon.
Energy diffusion from relativistic spontaneous localization

Daniel Bedingham Imperial College London
May 30, 2013

PIRSA:13050068
Astrophysics
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.
Nanoparticle interferometry: experimental tests of the quantum superposition principle at high mass and complexity.

Markus Arndt Technische Universität Wien

May 29, 2013

PIRSA:13050067
Negativity , Contextuality, Magic and the Power of Quantum Computation

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

PIRSA:13050084
High Energy Physics
Path Integrals, Reality and Generalizations of Quantum Theory

Adrian Kent University of Cambridge
May 29, 2013

PIRSA:13050065
Quantum Physics

Quantum Physics
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 Physics

High Energy Physics

Title	Date	Collection	Type	Info
Time, cosmology and quantum foundations	2013‑05‑31	The Quantum Landscape 2013	Conference	View details
Towards a realist's interpretation of the path integral	2013‑05‑31	The Quantum Landscape 2013	Conference	View details
Generalizations of Quantum Theory	2013‑05‑30	The Quantum Landscape 2013	Conference	View details
CDT without preferred foliation	2013‑05‑30	Quantum Gravity	Scientific Series	View details
Conjugates, Correlation and the Jordan Structure of Finite-Dimensional Quantum Theory	2013‑05‑30	The Quantum Landscape 2013	Conference	View details
Why look beyond quantum theory?	2013‑05‑30	The Quantum Landscape 2013	Conference	View details
Fuzzballs to Firewalls: A Post-Firewall Review of the Fuzzball Proposal: Lecture 1	2013‑05‑30		Scientific Series	View details
Energy diffusion from relativistic spontaneous localization	2013‑05‑30	The Quantum Landscape 2013	Conference	View details
Nanoparticle interferometry: experimental tests of the quantum superposition principle at high mass and complexity.	2013‑05‑29	The Quantum Landscape 2013	Scientific Series	View details
Negativity , Contextuality, Magic and the Power of Quantum Computation	2013‑05‑29	The Quantum Landscape 2013	Conference	View details
Path Integrals, Reality and Generalizations of Quantum Theory	2013‑05‑29	The Quantum Landscape 2013	Conference	View details
Constraints on generalizations of quantum theory	2013‑05‑28	The Quantum Landscape 2013	Conference	View details

Supported by

Format results

Time, cosmology and quantum foundations

Towards a realist's interpretation of the path integral

Generalizations of Quantum Theory

CDT without preferred foliation

Conjugates, Correlation and the Jordan Structure of Finite-Dimensional Quantum Theory

Why look beyond quantum theory?

Fuzzballs to Firewalls: A Post-Firewall Review of the Fuzzball Proposal: Lecture 1

Energy diffusion from relativistic spontaneous localization

Nanoparticle interferometry: experimental tests of the quantum superposition principle at high mass and complexity.

Negativity , Contextuality, Magic and the Power of Quantum Computation

Path Integrals, Reality and Generalizations of Quantum Theory

Constraints on generalizations of quantum theory

Time, cosmology and quantum foundations

Towards a realist's interpretation of the path integral

Generalizations of Quantum Theory

CDT without preferred foliation

Conjugates, Correlation and the Jordan Structure of Finite-Dimensional Quantum Theory

Why look beyond quantum theory?

Fuzzballs to Firewalls: A Post-Firewall Review of the Fuzzball Proposal: Lecture 1

Energy diffusion from relativistic spontaneous localization

Nanoparticle interferometry: experimental tests of the quantum superposition principle at high mass and complexity.

Negativity , Contextuality, Magic and the Power of Quantum Computation

Path Integrals, Reality and Generalizations of Quantum Theory

Constraints on generalizations of quantum theory