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Search results in Quantum Physics from PIRSA

1429 - 1440 of 2234 Results

A Non-Local Reality: Is there a Phase Uncertainty in Quantum Mechanics?
- Niayesh Afshordi University of Waterloo
- Elizabeth Gould Arthur B. McDonald Canadian Astroparticle Physics Research Institute
September 03, 2013

PIRSA:13090064
Quantum Physics
From empirical practice to observables and the action principle

Bruno Hartmann
June 25, 2013

PIRSA:13060019
Quantum Physics
Weak values: their meaning and uses in quantum foundations.

Howard Wiseman Griffith University
June 24, 2013

PIRSA:13060018
Quantum Physics
Generalized Relative Entropies, Entanglement Monotones and One-Shot Information Theory

Nilanjana Datta University of Cambridge
June 17, 2013

PIRSA:13060003
Quantum Physics
Quantum Factoring with Trapped Ions - A test of scalability

Isaac Chuang Massachusetts Institute of Technology (MIT)
June 12, 2013

PIRSA:13060002
Quantum Physics
Quantum Measurement in the Real World

Aephraim Steinberg University of Toronto
June 05, 2013

PIRSA:13060001
Quantum Physics
Characterizing quantum non-locality: a histories approach

Joe Henson BNP Paribas Asset Management London
May 31, 2013

PIRSA:13050073
Quantum Physics
Time, cosmology and quantum foundations

Lee Smolin Perimeter Institute for Theoretical Physics
May 31, 2013

PIRSA:13050072
Quantum Physics

Astrophysics
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
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
The Quantum-Mechanical Measurement Problem and the Foundations of Statistical Mechanics

David Albert Columbia University
May 28, 2013

PIRSA:13050062
Quantum Physics

A Non-Local Reality: Is there a Phase Uncertainty in Quantum Mechanics?
- Niayesh Afshordi University of Waterloo
- Elizabeth Gould Arthur B. McDonald Canadian Astroparticle Physics Research Institute
September 03, 2013

PIRSA:13090064
Quantum Physics
A century after the advent of Quantum Mechanics and General Relativity, both theories enjoy incredible empirical success, constituting the cornerstones of modern physics. Yet, paradoxically, they suffer from deep-rooted, so-far intractable, conflicts. Motivations for violations of the notion of
relativistic locality include the Bell's inequalities for hidden variable theories, the cosmological horizon problem, and Lorentz-violating approaches to quantum geometrodynamics, such as Horava-Lifshitz gravity. Here, we explore a recent proposal for a ``real ensemble'' non-local description of quantum mechanics, in which ``particles'' can copy each others' observables AND phases, independent of their spatial separation. We first specify the exact theory, ensuring that it is consistent and has (ordinary) quantum mechanics as a fixed point, where all particles with the same observables have the same phases. We then study the stability of this fixed point numerically, and analytically, for simple models. We provide evidence that most systems (in our study) are locally stable to small deviations from quantum mechanics, and furthermore, the phase variance per observable, as well as systematic deviations from quantum mechanics, decay as ~ (EnergyXTime)^{-n}, where n > 2. Interestingly, this convergence is controlled by the absolute value of energy (and not energy difference). Finally, we discuss different issues related to this theory, as well as potential implications for early universe, and the cosmological constant problem.
From empirical practice to observables and the action principle

Bruno Hartmann
June 25, 2013

PIRSA:13060019
Quantum Physics
Physical theories ought to be built up from colloquial notions such as ’long bodies’, ’energetic sources’ etc. in terms of which one can define pre-theoretic ordering relations such as ’longer than’, ’more energetic than’. One of the questions addressed in previous work is how to make the transition from these pre-theoretic notions to quantification, such as making the transition from the ordering relation of ’longer than’ (if one body covers the other) to the notion of how much longer. In similar way we introduce dynamical notions ’more impulse’ (if in a collision one object overruns the other) and ’more energetic’ (if the effect of one source exceeds the effect of the other). In a physical model - built by coupling congruent standard actions - those basic pre-theoretic notions become measurable. We derive all (classical and relativistic) equations between basic physical quantities of Energy, Momentum and Inertial Mass and ultimately the principle of least action.
Weak values: their meaning and uses in quantum foundations.

Howard Wiseman Griffith University
June 24, 2013

PIRSA:13060018
Quantum Physics
Weak values were introduced by Aharonov, Albert, and Vaidman 25 years ago, but it is only in the last 10 years that they have begun to enter into mainstream physics. I will introduce weak values as done by AAV, but then give them a modern definition in terms of generalized measurements. I will discuss their properties and their uses in experiment. Finally I will talk about what they have to contribute to quantum foundations.
Generalized Relative Entropies, Entanglement Monotones and One-Shot Information Theory

Nilanjana Datta University of Cambridge
June 17, 2013

PIRSA:13060003
Quantum Physics
We introduce two relative entropy quantities called the min- and max-relative
entropies and discuss their properties and operational meanings.

These relative entropies act as parent quantities for tasks such as data compression, information
transmission and entanglement manipulation in one-shot information theory. Moreover, they lead us to define entanglement monotones which have interesting operational interpretations.
Quantum Factoring with Trapped Ions - A test of scalability

Isaac Chuang Massachusetts Institute of Technology (MIT)
June 12, 2013

PIRSA:13060002
Quantum Physics
Shor's algorithm can be a meaningful test for experimental quantum processing systems, when suitably realized. I present results from a recent implemenation of quantum factoring using trapped ion qubits, demonstrating feed-forward control, use of quantum memory during computation, and cascaded three-qubit gates. Such capabilities are necessary ingredients for a future large-scale,
fault-tolerant quantum computing system.
Quantum Measurement in the Real World

Aephraim Steinberg University of Toronto
June 05, 2013

PIRSA:13060001
Quantum Physics
While quantum measurement remains the central philosophical conundrum of quantum mechanics, it has recently grown into a respectable (read: experimental!) discipline as well. New perspectives on measurement have grown out of new technological possibilities, but also out of
attempts to design systems for quantum information processing, which promise to be exponentially more powerful than any possible classical computer. I will try to give a flavour about some of these perspectives, focussing largely on a particular paradigm known as "weak measurement."
Weak measurement is a natural extension of a pragmatic view of what it means to measure something about a quantum system, yet leads to some rather surprising results. I will describe a few examples of our recent experiments using weak measurement to probe fundamental issues in uantum mechanics such as what the minimum disturbance due to a quantum measurement is. I will also argue that there are regimes in which weak measurement offers a practical advantage for sensitive measurements.
Characterizing quantum non-locality: a histories approach

Joe Henson BNP Paribas Asset Management London
May 31, 2013

PIRSA:13050073
Quantum Physics
Characterising quantum non-locality using simple physical principles has become a hot topic in quantum foundations of late. In the simpler case of local hidden variable models, the space of allowed correlations can be characterised by requiring that there exists a joint probability distribution over all possible experimental outcomes, from which the experimental probabilities arise as marginals. This follows from Bell’s causality condition. But the existing characterisations of quantum correlations are far from being so straightforward.
Motivated by a histories outlook, we propose the following condition: there exists a positive semi-definite matrix in which the indices run over all possible experimental outcomes, from which the experimental probabilities arise as “marginals” in a similar way. This is a much simpler condition than the usual statement of the existence of a quantum model for the probabilities, and suggests an underlying connection with Bell’s derivation of his bound on local correlations. I will outline existing proofs that this condition places strong bounds on correlations consistent with QM, and ask whether it could completely characterise quantum non-locality
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.
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
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
The Quantum-Mechanical Measurement Problem and the Foundations of Statistical Mechanics

David Albert Columbia University
May 28, 2013

PIRSA:13050062
Quantum Physics

Title	Date	Collection	Type	Info
A Non-Local Reality: Is there a Phase Uncertainty in Quantum Mechanics?	2013‑09‑03	Quantum Foundations	Scientific Series	View details
From empirical practice to observables and the action principle	2013‑06‑25	Quantum Foundations	Scientific Series	View details
Weak values: their meaning and uses in quantum foundations.	2013‑06‑24	Quantum Foundations	Scientific Series	View details
Generalized Relative Entropies, Entanglement Monotones and One-Shot Information Theory	2013‑06‑17	Perimeter Institute Quantum Discussions	Scientific Series	View details
Quantum Factoring with Trapped Ions - A test of scalability	2013‑06‑12	Colloquium	Scientific Series	View details
Quantum Measurement in the Real World	2013‑06‑05	Colloquium	Scientific Series	View details
Characterizing quantum non-locality: a histories approach	2013‑05‑31	The Quantum Landscape 2013	Conference	View details
Time, cosmology and quantum foundations	2013‑05‑31	The Quantum Landscape 2013	Conference	View details
Generalizations of Quantum Theory	2013‑05‑30	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
The Quantum-Mechanical Measurement Problem and the Foundations of Statistical Mechanics	2013‑05‑28	The Quantum Landscape 2013	Conference	View details

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Format results

A Non-Local Reality: Is there a Phase Uncertainty in Quantum Mechanics?

From empirical practice to observables and the action principle

Weak values: their meaning and uses in quantum foundations.

Generalized Relative Entropies, Entanglement Monotones and One-Shot Information Theory

Quantum Factoring with Trapped Ions - A test of scalability

Quantum Measurement in the Real World

Characterizing quantum non-locality: a histories approach

Time, cosmology and quantum foundations

Generalizations of Quantum Theory

Path Integrals, Reality and Generalizations of Quantum Theory

Constraints on generalizations of quantum theory

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

A Non-Local Reality: Is there a Phase Uncertainty in Quantum Mechanics?

From empirical practice to observables and the action principle

Weak values: their meaning and uses in quantum foundations.

Generalized Relative Entropies, Entanglement Monotones and One-Shot Information Theory

Quantum Factoring with Trapped Ions - A test of scalability

Quantum Measurement in the Real World

Characterizing quantum non-locality: a histories approach

Time, cosmology and quantum foundations

Generalizations of Quantum Theory

Path Integrals, Reality and Generalizations of Quantum Theory

Constraints on generalizations of quantum theory

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