Conference

Displaying 3133 - 3144 of 5053

Photons and Quantum Gravity in Astrophysics
- Robert Nemiroff Michigan Technological University
- Giovanni Amelino-Camelia University of Naples Federico II
- Niayesh Afshordi University of Waterloo
- Joao Magueijo Imperial College London
- Alfio Bonanno National Institute for Astrophysics (INAF)
- Robert Brandenberger McGill University - Department of Physics
October 22, 2012

PIRSA:12100085
General Relativity & Quantum Cosmology

High Energy Physics
Lorentz Invariance Violation searches with HESS

Julien Bolmont Sorbonne University

October 22, 2012

PIRSA:12100084
Is there a MesoScale in Quantum Gravity? Is it a Non-Locality Scale?
- Laurent Freidel Perimeter Institute for Theoretical Physics
- Stefano Liberati SISSA International School for Advanced Studies
- Dionigi Benincasa
October 22, 2012

PIRSA:12100082
General Relativity & Quantum Cosmology
The cosmological constant and the emergence of the continuum

Lorenzo Sindoni Max Planck Institute for Gravitational Physics - Albert Einstein Institute (AEI)
October 22, 2012

PIRSA:12100081
Astrophysics
An analogue model lesson for the cosmological constant

Stefano Liberati SISSA International School for Advanced Studies
October 22, 2012

PIRSA:12100080
Astrophysics
Improved test of the Equivalence Principle as a probe of quantum gravity
- James Overduin Towson University
- Daniel Sudarsky Universidad Nacional Autónoma De Mexico (UNAM)
October 22, 2012

PIRSA:12100127
General Relativity & Quantum Cosmology
Matter-wave clocks

Holger Mueller University of California, Berkeley
October 22, 2012

PIRSA:12100124
General Relativity & Quantum Cosmology
Causal Constraints on Possible Measurements

Leron Borsten Heriot-Watt University
June 28, 2012

PIRSA:12060078
High Energy Physics
Holographic Mutual Information is Monogamous

Patrick Hayden Stanford University
June 28, 2012

PIRSA:12060070
Quantum Physics
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
High Energy Physics

Photons and Quantum Gravity in Astrophysics
- Robert Nemiroff Michigan Technological University
- Giovanni Amelino-Camelia University of Naples Federico II
- Niayesh Afshordi University of Waterloo
- Joao Magueijo Imperial College London
- Alfio Bonanno National Institute for Astrophysics (INAF)
- Robert Brandenberger McGill University - Department of Physics
October 22, 2012

PIRSA:12100085
General Relativity & Quantum Cosmology

High Energy Physics
Asymptotically safe inflation and CMB polarization
The presence of complex critical exponents in the scaling behavior of the Newton constant and Cosmological constant has dramatic consequences at the inflation scale. In particular an infinite number of unstable de-Sitter vacua emerges from an effective quantum gravitational action. In this framework, the possibility of detecting specific signaturesof a non-gaussian fixed point of the gravitational interactions in the CMB polarization spectrum will then be discussed.

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Cosmological windows such as CMB polarization and 21cm redshift surveys to probe Planck-scale physics

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Quantum gravity and a chiral signature in gravity waves
I show how quantum gravity could lead to a chiral signature in the graviational wave background, proportional to the imaginary part of the Immirzi parameter. This would leave a distinctive imprint in the polarization of the cosmic microwave background. I will discuss how this isue is closely related to that of identifying the ground of base state for quantum gravity.

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A Possible Bound on Spectral Dispersion from Fermi-Detected Gamma Ray Burst 090510A
Three photons spanning about 30 GeV arrived within about one millisecond from the Fermi-detected GRB 090510A at a redshift of about 0.9. Although conceivably a > 3Ïƒ statistical fluctuation when taken at face value this photon bunch -- quite possibly a classic GRB pulse -- leads to a relatively tight bound on the ability of our universe to disperse high energy photons. Specifically given a generic dispersion relation where the time delay is proportional to the photon energy to the first power the limit on the dispersion strength is k1 < 1.61Ã—10-5 sec Gpc-1 GeV-1. In the context of some theories of quantum gravity this conservative bound translates into an minimum energy scale greater than 525 m_Planck suggesting that spacetime is smooth at energies perhaps three orders of magnitude over the Planck mass.
Lorentz Invariance Violation searches with HESS

Julien Bolmont Sorbonne University

October 22, 2012

PIRSA:12100084

The high flux and variability of the blazar PKS 2155-304 as observed by H.E.S.S. during the night of 28 July 2006 allowed a very high precision search for Quantum Gravity-induced energy-dependent time lags. In this talk, I will review the results published by the H.E.S.S. collaboration on this topic. In particular, I will emphasize the latest results obtained using a likelihood fit to study individual photon data. With this method and a proper error calibration procedure, a very high precision measurement was achieved leading to the best constraints on linear and quadratic terms of the dispersion relations obtained with an AGN so far.
Is there a MesoScale in Quantum Gravity? Is it a Non-Locality Scale?
- Laurent Freidel Perimeter Institute for Theoretical Physics
- Stefano Liberati SISSA International School for Advanced Studies
- Dionigi Benincasa
October 22, 2012

PIRSA:12100082
General Relativity & Quantum Cosmology
The cosmological constant and the emergence of the continuum

Lorenzo Sindoni Max Planck Institute for Gravitational Physics - Albert Einstein Institute (AEI)
October 22, 2012

PIRSA:12100081
Astrophysics
Naturalness problems that could be signaling the necessity a completion of an effective field theory with the introduction of an otherwise overlooked ingredient. The cosmological constant problem can be seen as a signal that the EFT for gravity, general relativity, is not correctly including the gravitational properties of the vacuum. Starting from the discussion of the a possible solution to this naturalness problem for a cc-like term in a BEC analogue model, I will briefly discuss how this particular mechanism can be extended, albeit in a preliminary form, to more genuine quantum gravity models like GFT, connecting in particular the problem of the determination of the gravitational couplings (and hence the hierarchies involved) to the appearance of a semiclassical space-time
An analogue model lesson for the cosmological constant

Stefano Liberati SISSA International School for Advanced Studies
October 22, 2012

PIRSA:12100080
Astrophysics
Analogue models of gravity have been a test field for many phenomena in quantum field theory on curved spacetimes. It was recently recognized that in some situations they can also provide toy models of emergent gravity. We shall review here such a model and address within it the nature and scale of the cosmological constrant trying to draw general lessons for emergent gravity scenarios.
Improved test of the Equivalence Principle as a probe of quantum gravity
- James Overduin Towson University
- Daniel Sudarsky Universidad Nacional Autónoma De Mexico (UNAM)
October 22, 2012

PIRSA:12100127
General Relativity & Quantum Cosmology
Current approaches to the problems of dark energy and unification generically predict the existence of new fields (quintessence dilatons etc.) that will in principle couple with different strengths to different standard-model fields. These different coupling strengths will cause test materials of different compositions to fall at different rates in the same gravitational field violating the Equivalence Principle the foundation of General Relativity. A sufficiently sensitive measurement of the relative accelerations of different test bodies in orbit around the earth could detect or rule out these new fields complementing existing or proposed experiments in high-energy physics (colliders) and observational cosmology (space telescopes). To do this convincingly such an experiment needs at least three test materials spanning the largest possible volume in the space of atomic and molecular properties and a sensitivity to EP violations of as little as a part in $10^{18}$ (attainable only in space and at low temperatures). I discuss one such experiment the Satellite Test of the Equivalence Principle which has reached an advanced stage of prototype development and is currently awaiting a path toward a flight program.
Matter-wave clocks

Holger Mueller University of California, Berkeley
October 22, 2012

PIRSA:12100124
General Relativity & Quantum Cosmology
Causal Constraints on Possible Measurements

Leron Borsten Heriot-Watt University
June 28, 2012

PIRSA:12060078
High Energy Physics
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 Physics
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
High Energy Physics
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	Speaker(s)	Date	Talk Type	Info link
Photons and Quantum Gravity in Astrophysics	Robert Nemiroff, Giovanni Amelino-Camelia, Niayesh Afshordi, Joao Magueijo, Alfio Bonanno, Robert Brandenberger	2012-10-22	Conference	View details
Lorentz Invariance Violation searches with HESS	Julien Bolmont	2012-10-22	Conference	View details
Is there a MesoScale in Quantum Gravity? Is it a Non-Locality Scale?	Laurent Freidel, Stefano Liberati, Dionigi Benincasa	2012-10-22	Conference	View details
The cosmological constant and the emergence of the continuum	Lorenzo Sindoni	2012-10-22	Conference	View details
An analogue model lesson for the cosmological constant	Stefano Liberati	2012-10-22	Conference	View details
Improved test of the Equivalence Principle as a probe of quantum gravity	James Overduin, Daniel Sudarsky	2012-10-22	Conference	View details
Matter-wave clocks	Holger Mueller	2012-10-22	Conference	View details
Causal Constraints on Possible Measurements	Leron Borsten	2012-06-28	Conference	View details
Holographic Mutual Information is Monogamous	Patrick Hayden	2012-06-28	Conference	View details
Quantum Tasks in Minkowski Space	Adrian Kent	2012-06-28	Conference	View details
Entanglement Generation in Relativistic Quantum Fields		2012-06-28	Conference	View details
On the Preparation of States in Nonlinear Quantum Mechanics	Nicolas Menicucci	2012-06-28	Conference	View details

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Format results

Photons and Quantum Gravity in Astrophysics

Lorentz Invariance Violation searches with HESS

Is there a MesoScale in Quantum Gravity? Is it a Non-Locality Scale?

The cosmological constant and the emergence of the continuum

An analogue model lesson for the cosmological constant

Improved test of the Equivalence Principle as a probe of quantum gravity

Matter-wave clocks

Causal Constraints on Possible Measurements

Holographic Mutual Information is Monogamous

Quantum Tasks in Minkowski Space

Entanglement Generation in Relativistic Quantum Fields

On the Preparation of States in Nonlinear Quantum Mechanics

Photons and Quantum Gravity in Astrophysics

Lorentz Invariance Violation searches with HESS

Is there a MesoScale in Quantum Gravity? Is it a Non-Locality Scale?

The cosmological constant and the emergence of the continuum

An analogue model lesson for the cosmological constant

Improved test of the Equivalence Principle as a probe of quantum gravity

Matter-wave clocks

Causal Constraints on Possible Measurements

Holographic Mutual Information is Monogamous

Quantum Tasks in Minkowski Space

Entanglement Generation in Relativistic Quantum Fields

On the Preparation of States in Nonlinear Quantum Mechanics