Quantum Physics

Displaying 1537 - 1548 of 2285

Quantum Computation vs. Firewalls

Daniel Harlow Massachusetts Institute of Technology (MIT)
February 26, 2013

PIRSA:13020138
Quantum Physics

High Energy Physics
12/13 PSI - Quantum Information Review Lecture 6

Andrew Childs University of Waterloo
February 26, 2013

PIRSA:13020116
Quantum Physics
Bounding the purification rank of mixed states

Gemma De Las Cuevas Universität Innsbruck
February 25, 2013

PIRSA:13020149
Quantum Physics
12/13 PSI - Quantum Information Review Lecture 5

Andrew Childs University of Waterloo
February 25, 2013

PIRSA:13020115
Quantum Physics
12/13 PSI - Quantum Information Review Lecture 4

Andrew Childs University of Waterloo
February 22, 2013

PIRSA:13020112
Quantum Physics
12/13 PSI - Quantum Information Review Lecture 3

Andrew Childs University of Waterloo
February 21, 2013

PIRSA:13020111
Quantum Physics
12/13 PSI - Quantum Information Review Lecture 2

Andrew Childs University of Waterloo
February 20, 2013

PIRSA:13020110
Quantum Physics
12/13 PSI - Quantum Information Review Lecture 1

Andrew Childs University of Waterloo
February 19, 2013

PIRSA:13020109
Quantum Physics
The structure of meaning in natural language: a big money quantum foundations spin-off.

Bob Coecke Quantinuum
February 12, 2013

PIRSA:13020131
Quantum Physics
A positive and local formalism for quantum theory

Robert Oeckl Universidad Nacional Autónoma De Mexico (UNAM)
February 05, 2013

PIRSA:13020125
Quantum Physics
Pinning of Fermionic Occupation Numbers

Christian Schilling ETH Zurich
January 21, 2013

PIRSA:13010105
Quantum Physics
Exotic topological order from quantum fractal code

Beni Yoshida Perimeter Institute for Theoretical Physics
January 14, 2013

PIRSA:13010101
Quantum Physics

Quantum Computation vs. Firewalls

Daniel Harlow Massachusetts Institute of Technology (MIT)
February 26, 2013

PIRSA:13020138
Quantum Physics

High Energy Physics
12/13 PSI - Quantum Information Review Lecture 6

Andrew Childs University of Waterloo
February 26, 2013

PIRSA:13020116
Quantum Physics
Bounding the purification rank of mixed states

Gemma De Las Cuevas Universität Innsbruck
February 25, 2013

PIRSA:13020149
Quantum Physics
A mixed state can be expressed as a sum of D tensor product matrices, where D is its operator Schmidt rank, or as the result of a purification with a purifying state of Schmidt rank D', where D' is its purification rank. The question whether D' can be upper bounded by D is important theoretically (to establish a description of mixed states with tensor networks), as well as numerically (as the first decomposition is more efficient, but the second one guarantees positive-semidefiniteness after truncation). Here we show that no upper bounds of the purification rank that depend only on operator Schmidt rank exist, but provide upper bounds that also depend on the number of eigenvalues. In addition, we formulate the approximation problem as a Semidefinite Program.
Joint work with N. Schuch, D. Perez-Garcia, and J. I. Cirac.
12/13 PSI - Quantum Information Review Lecture 5

Andrew Childs University of Waterloo
February 25, 2013

PIRSA:13020115
Quantum Physics
12/13 PSI - Quantum Information Review Lecture 4

Andrew Childs University of Waterloo
February 22, 2013

PIRSA:13020112
Quantum Physics
12/13 PSI - Quantum Information Review Lecture 3

Andrew Childs University of Waterloo
February 21, 2013

PIRSA:13020111
Quantum Physics
12/13 PSI - Quantum Information Review Lecture 2

Andrew Childs University of Waterloo
February 20, 2013

PIRSA:13020110
Quantum Physics
12/13 PSI - Quantum Information Review Lecture 1

Andrew Childs University of Waterloo
February 19, 2013

PIRSA:13020109
Quantum Physics
The structure of meaning in natural language: a big money quantum foundations spin-off.

Bob Coecke Quantinuum
February 12, 2013

PIRSA:13020131
Quantum Physics
A positive and local formalism for quantum theory

Robert Oeckl Universidad Nacional Autónoma De Mexico (UNAM)
February 05, 2013

PIRSA:13020125
Quantum Physics
The general boundary formulation (GBF) is an atemporal, but spacetime local formulation of quantum theory. Usually it is presented in terms of the amplitude formalism, which, in the presence of a background time, recovers the pure state formalism of the standard formulation of quantum theory. After reviewing the essentials of the amplitude formalism I will introduce a new "positive formalism", which recovers instead a mixed state formalism. This allows to define general quantum operations within the GBF and opens it to quantum information theory. Moreover, the transition to the positive formalism eliminates operationally irrelevant structure, making the extraction of measurement probabilities more direct. As a consequence, the probability interpretation takes on a remarkably simple and compelling form. I shall describe implications of the positive formalism, both for our understanding of quantum theory and for the practical formulation of quantum theories. I also observe a certain convergence with Lucien Hardy's operator tensor formulation of quantum theory, on which I hope to comment
Pinning of Fermionic Occupation Numbers

Christian Schilling ETH Zurich
January 21, 2013

PIRSA:13010105
Quantum Physics
The problem of determining and describing the family of 1-particle reduced density operators (1-RDO) arising from N-fermion pure states (viapartial trace) is known as the fermionic quantum marginal problem. We present its solution, a multitude of constraints on the eigenvalues of the 1-RDO, generalizing the Pauli exclusion principle. To explore the relevance of these constraints we study an analytically solvable model of N fermions in a harmonic potential and determine the spectral `trajectory' corresponding to the ground state as function of the fermion-fermion interaction strength.Intriguingly, we find that the occupation numbers are almost, but not exactly, pinned to the boundary of the allowed region (quasi-pinned). Our findings suggest a generalization of the Hartree-Fock approximation.

see also: http://arxiv.org/abs/1210.5531
Exotic topological order from quantum fractal code

Beni Yoshida Perimeter Institute for Theoretical Physics
January 14, 2013

PIRSA:13010101
Quantum Physics
We present a family of three-dimensional local quantum codes with pairs of fractal logical operators. It has two polynomials over finite fields as input parameters which generate fractal shapes of anti-commuting logical operators, and possesses exotic topological order with quantum glassiness which is beyond descriptions of conventional topological field theory. A necessary and sufficient condition for being free from string-like logical operators is obtained under which the model works as marginally self-correcting quantum memory. We also provide theoretical tools to analyze physical and coding properties of translation symmetric stabilizer Hamiltonians.

Title	Speaker(s)	Date	Talk Type	Info link
Quantum Computation vs. Firewalls	Daniel Harlow	2013-02-26	Scientific Series	View details
12/13 PSI - Quantum Information Review Lecture 6	Andrew Childs	2013-02-26	Course	View details
Bounding the purification rank of mixed states	Gemma De Las Cuevas	2013-02-25	Scientific Series	View details
12/13 PSI - Quantum Information Review Lecture 5	Andrew Childs	2013-02-25	Course	View details
12/13 PSI - Quantum Information Review Lecture 4	Andrew Childs	2013-02-22	Course	View details
12/13 PSI - Quantum Information Review Lecture 3	Andrew Childs	2013-02-21	Course	View details
12/13 PSI - Quantum Information Review Lecture 2	Andrew Childs	2013-02-20	Course	View details
12/13 PSI - Quantum Information Review Lecture 1	Andrew Childs	2013-02-19	Course	View details
The structure of meaning in natural language: a big money quantum foundations spin-off.	Bob Coecke	2013-02-12	Scientific Series	View details
A positive and local formalism for quantum theory	Robert Oeckl	2013-02-05	Scientific Series	View details
Pinning of Fermionic Occupation Numbers	Christian Schilling	2013-01-21	Scientific Series	View details
Exotic topological order from quantum fractal code	Beni Yoshida	2013-01-14	Scientific Series	View details

Supported by

Format results

Quantum Computation vs. Firewalls

12/13 PSI - Quantum Information Review Lecture 6

Bounding the purification rank of mixed states

12/13 PSI - Quantum Information Review Lecture 5

12/13 PSI - Quantum Information Review Lecture 4

12/13 PSI - Quantum Information Review Lecture 3

12/13 PSI - Quantum Information Review Lecture 2

12/13 PSI - Quantum Information Review Lecture 1

The structure of meaning in natural language: a big money quantum foundations spin-off.

A positive and local formalism for quantum theory

Pinning of Fermionic Occupation Numbers

Exotic topological order from quantum fractal code

Quantum Computation vs. Firewalls

12/13 PSI - Quantum Information Review Lecture 6

Bounding the purification rank of mixed states

12/13 PSI - Quantum Information Review Lecture 5

12/13 PSI - Quantum Information Review Lecture 4

12/13 PSI - Quantum Information Review Lecture 3

12/13 PSI - Quantum Information Review Lecture 2

12/13 PSI - Quantum Information Review Lecture 1

The structure of meaning in natural language: a big money quantum foundations spin-off.

A positive and local formalism for quantum theory

Pinning of Fermionic Occupation Numbers

Exotic topological order from quantum fractal code