Talks

10957 - 10968 of 16754 Results

What is the Universe Made Of? The Case for Dark Matter and Dark Energy

Cliff Burgess McMaster University

July 13, 2012

PIRSA:12070004

Cosmology
Entanglement, Holography, and the Quantum Phases of Matter

Subir Sachdev Harvard University

July 13, 2012

PIRSA:12070010
Entangling Superconductivity and antiferromagnetism: Quantum Monte Carlo without the sign Problem

Subir Sachdev Harvard University

July 11, 2012

PIRSA:12070009

Condensed Matter
Smash, Bang, Boom: Fundamental Physics at the LHC

Natalia Toro Stanford University

July 11, 2012

PIRSA:12070002

Particle Physics
The Path Integral Interpretation of Quantum Mechanics

Fay Dowker Imperial College London

July 10, 2012

PIRSA:12070001
TBA

Itay Yavin McMaster University

July 10, 2012

PIRSA:12070011
Modern Cosmology

Niayesh Afshordi University of Waterloo

July 09, 2012

PIRSA:12070003

Cosmology
Causal Constraints on Possible Measurements

Leron Borsten Heriot-Watt University

June 28, 2012

PIRSA:12060078

Quantum Fields and Strings
Holographic Mutual Information is Monogamous

Patrick Hayden Stanford University

June 28, 2012

PIRSA:12060070

Quantum Information
Quantum Tasks in Minkowski Space

Adrian Kent University of Cambridge

June 28, 2012

PIRSA:12060062

Mathematical physics
Entanglement Generation in Relativistic Quantum Fields

June 28, 2012

PIRSA:12060068
On the Preparation of States in Nonlinear Quantum Mechanics

Nicolas Menicucci Royal Melbourne Institute of Technology University (RMIT)

June 28, 2012

PIRSA:12060048

Quantum Fields and Strings

What is the Universe Made Of? The Case for Dark Matter and Dark Energy

Cliff Burgess McMaster University

July 13, 2012

PIRSA:12070004

Cosmology

For the first time in human thought it is now
possible to observationally determine how much matter is in the Universe as a
whole. These observations strongly support the “Concordance Model” of Hot Big
Bang Cosmology, and reinforce earlier indications that ordinary matter (atoms,
nuclei and electrons) make up at present at most 4% of the total of the
Universal energy density. The big surprise was that the rest consists of *two*
kinds of unknown forms of matter: the so-called Dark Matter and Dark Energy.
This talk summarizes for non-specialists the various lines of evidence for
their existence, and some of the theoretical ideas which have been proposed to
account for their properties
Entanglement, Holography, and the Quantum Phases of Matter

Subir Sachdev Harvard University

July 13, 2012

PIRSA:12070010
Entangling Superconductivity and antiferromagnetism: Quantum Monte Carlo without the sign Problem

Subir Sachdev Harvard University

July 11, 2012

PIRSA:12070009

Condensed Matter

It has long been known that a metal near an instability to antiferromagnetism also has a weak-coupling Cooper instability to spin-singlet d-wave-like superconductivity. However, the theory of the antiferromagnetic quantum critical point flows to strong-coupling in two spatial dimensions, and so the fate of the superconductivity has also been unclear. I will describe a method to realize the generic antiferromagnetic quantum critical in a metal in a sign-problem-free Monte Carlo simulation. Results showing Fermi surface reconstruction and unconventional spin-singlet superconductivity across the critical point are obtained.
Smash, Bang, Boom: Fundamental Physics at the LHC

Natalia Toro Stanford University

July 11, 2012

PIRSA:12070002

Particle Physics

The world's most ambitious scientific experiment is buried 100 meters underground, straddling Switzerland and France. A billion times every minute, the Large Hadron Collider (LHC) slams together protons, while four giant detectors watch closely. - So how does the Large Hadron Collider work? - Why can slamming tiny particles into each other provide clues about the nature of all space and time? - What mysteries are physicists trying to solve with data from the LHC? - How does the cutting edge of particle physics relate to the world around us, from the patterns of stars in the sky to the fact that they shine at all? Natalia Toro, PI Faculty, works at the intersection of theories and hard data. She will explain how complex collision data from the LHC is being digested and examined right now, and how it may set the course for the science of the future.
The Path Integral Interpretation of Quantum Mechanics

Fay Dowker Imperial College London

July 10, 2012

PIRSA:12070001
TBA

Itay Yavin McMaster University

July 10, 2012

PIRSA:12070011
Modern Cosmology

Niayesh Afshordi University of Waterloo

July 09, 2012

PIRSA:12070003

Cosmology

This presentation will cover a number of topics in cosmology today including dark energy, dark matter and the cosmological constant.
Causal Constraints on Possible Measurements

Leron Borsten Heriot-Watt University

June 28, 2012

PIRSA:12060078

Quantum Fields and Strings

A crucial question in any approach to quantum information processing is: first, how are classical bits encoded physically in the quantum system, second, how are they then manipulated and, third, how are they finally read out? These questions are particularly challenging when investigating quantum information processing in a relativistic spacetime. An obvious framework for such an investigation is relativistic quantum field theory. Here, progress is hampered by the lack of a universally applicable rule for calculating the probabilities of the outcomes of ideal measurements on a relativistic quantum field in a collection of spacetime regions. Indeed, a straightforward relativistic generalisation of the non-relativistic formula for these probabilities leads to superluminal signalling.

Motivated by these considerations we ask what interventions/ideal measurements can we in principle make, taking causality as our guiding criterion. In the course of this analysis we reconsider various aspects of ideal measurements in QFT, detector models and the probability rules themselves. In particular, it is shown that an ideal measurement of a one–particle wave packet state of a relativistic quantum field in Minkowski spacetime enables superluminal signalling. The result holds for a measurement that takes place over an intervention region in spacetime whose extent in time in some frame is longer than the light crossing time of the packet in that frame.
Holographic Mutual Information is Monogamous

Patrick Hayden Stanford University

June 28, 2012

PIRSA:12060070

Quantum Information

I'll describe a special information-theoretic property of quantum field theories with holographic duals: the mutual informations among arbitrary disjoint spatial regions A,B,C obey the inequality I(A:BC) >= I(A:B)+I(A:C), provided entanglement entropies are given by the Ryu-Takayanagi formula. Inequalities of this type are known as monogamy relations and are characteristic of measures of quantum entanglement. This suggests that correlations in holographic theories arise primarily from entanglement rather than classical correlations. Moreover, monogamy property implies that the Ryu-Takayanagi formula is consistent with all known general inequalities obeyed by the entanglement entropy, including an infinite set recently discovered by Cadney, Linden, and Winter; this constitutes significant evidence in favour of its validity.
Quantum Tasks in Minkowski Space

Adrian Kent University of Cambridge

June 28, 2012

PIRSA:12060062

Mathematical physics

The fundamental properties of quantum information and its applications to computing and cryptography have been greatly illuminated by considering information-theoretic tasks that are provably possible or impossible within non-relativistic quantum mechanics. In this talk I describe a general framework for defining tasks within (special) relativistic quantum theory and illustrate it with examples from relativistic quantum cryptography.
Entanglement Generation in Relativistic Quantum Fields

June 28, 2012

PIRSA:12060068

We present a general, analytic recipe to compute the entanglement that is generated between arbitrary, discrete modes of bosonic quantum fields by Bogoliubov transformations. Our setup allows the complete characterization of the quantum correlations in all Gaussian field states. Additionally, it holds for all Bogoliubov transformations. These are commonly applied in quantum optics for the description of squeezing operations, relate the modedecompositions of observers in different regions of curved spacetimes, and describe observers moving along non-stationary trajectories. We focus on a quantum optical example in a cavity quantum electrodynamics setting: an uncharged scalar field within a cavity provides a model for an optical resonator, in which entanglement is created by non-uniform acceleration.We show that the amount of generated entanglement can be magnified by initialsingle-mode squeezing, for which we provide an explicit formula.Applications to quantum fields in curved spacetimes, such as an expanding universe, are discussed.
On the Preparation of States in Nonlinear Quantum Mechanics

Nicolas Menicucci Royal Melbourne Institute of Technology University (RMIT)

June 28, 2012

PIRSA:12060048

Quantum Fields and Strings

Recent analysis of closed timelike curves from an information-theoretic perspective has led to contradictory conclusions about their information-processing power. One thing is generally agreed upon, however, which is that if such curves exist, the quantum-like evolution they imply would be nonlinear, but the physical interpretation of such theories is still unclear. It is known that any operationally verifiable instance of a nonlinear, deterministic evolution on some set of pure states makes the density matrix inadequate for representing mixtures of those pure states. We re-cast the problem in the language of operational quantum mechanics, building on previous work to show that the no-signalling requirement leads to a splitting of the equivalence classes of preparation procedures. This leads to the conclusion that any non-linear theory satisfying certain minimal conditions must be regarded as inconsistent unless it contains distinct representations for the two different kinds of mixtures, and incomplete unless it contains a rule for determining the physical preparations associated with each type. We refer to this as the `preparation problem' for nonlinear theories.

Title	Date	Collection	Type	Info
What is the Universe Made Of? The Case for Dark Matter and Dark Energy	2012‑07‑13	ISSYP 2012		View details
Entanglement, Holography, and the Quantum Phases of Matter	2012‑07‑13	Quantum Matter	Scientific Series	View details
Entangling Superconductivity and antiferromagnetism: Quantum Monte Carlo without the sign Problem	2012‑07‑11	Quantum Matter	Scientific Series	View details
Smash, Bang, Boom: Fundamental Physics at the LHC	2012‑07‑11	Particle Physics		View details
The Path Integral Interpretation of Quantum Mechanics	2012‑07‑10	Quantum Foundations	Scientific Series	View details
TBA	2012‑07‑10	Particle Physics	Other	View details
Modern Cosmology	2012‑07‑09	Cosmology and Gravitation		View details
Causal Constraints on Possible Measurements	2012‑06‑28	Relativistic Quantum Information - 2012	Conference	View details
Holographic Mutual Information is Monogamous	2012‑06‑28	Relativistic Quantum Information - 2012	Conference	View details
Quantum Tasks in Minkowski Space	2012‑06‑28	Relativistic Quantum Information - 2012	Conference	View details
Entanglement Generation in Relativistic Quantum Fields	2012‑06‑28	Relativistic Quantum Information - 2012	Conference	View details
On the Preparation of States in Nonlinear Quantum Mechanics	2012‑06‑28	Relativistic Quantum Information - 2012	Conference	View details

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