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Quasiprobability representations of qubits

November 13, 2012

PIRSA:12110070
Anomaly-induced transport and thermodynamics

Kristan Jensen University of Victoria
November 13, 2012

PIRSA:12110047
Quantum Fields and Strings
Stealthy, Composite Stops

Philip Tanedo Cornell University
November 13, 2012

PIRSA:12110063
Particle Physics
Recent progress on de Sitter S-matrix

Ian Morrison West Chester University
November 13, 2012

PIRSA:12110043
Cosmology
Statistical Mechanics - Lecture 2

John Berlinsky McMaster University

November 13, 2012

PIRSA:12110020
Quantum Field Theory 2 - Lecture 2

Francois David CEA Saclay
November 13, 2012

PIRSA:12110001
Quantum Fields and Strings
Statistical Mechanics - Lecture 1

John Berlinsky McMaster University

November 12, 2012

PIRSA:12110019
Quantum Field Theory 2 - Lecture 1

Francois David CEA Saclay
November 12, 2012

PIRSA:12110000
Quantum Fields and Strings
Geometric algebra techniques in flux compactifications

Calin Lazaroiu Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering
November 09, 2012

PIRSA:12110058
Mathematical physics
Dynamical evaporation of quantum horizons
November 08, 2012

PIRSA:12110064
Quantum Gravity
Discovery of the Higgs Boson: Sweet Dream or Nightmare

Melissa Franklin Harvard University

November 07, 2012

PIRSA:12110055
Optimal quantum self-tests based on binary nonlocal XOR games

November 07, 2012

PIRSA:12110067

Quasiprobability representations of qubits

November 13, 2012

PIRSA:12110070

Negativity in a quasi-probability representation is typically interpreted as an indication of nonclassical behavior. However, this does not preclude bases that are non-negative from having interesting applications---the single-qubit stabilizer states have non-negative Wigner functions and yet play a fundamental role in many quantum information tasks. We determine what other sets of quantum states and measurements of a qubit can be non-negative in a quasiprobability representation, and identify nontrivial groups of unitary transformations that permute such states. These sets of states and measurements are analogous to the single-qubit stabilizer states. We show that no quasiprobability representation of a qubit can be non-negative for more than two bases in any plane of the Bloch sphere. Furthermore, there is a single family of sets of four bases that can be non-negative in an arbitrary quasiprobability representation of a qubit. We provide an exhaustive list of the sets of single-qubit bases that are nonnegative in some quasiprobability representation and are also closed under a group of unitary transformations, revealing two families of such sets of three bases. We also show that not all two-qubit Clifford transformations can preserve non-negativity in any quasiprobability representation that is non-negative for the computational basis. This is in stark contrast to the qutrit case, in which the discrete Wigner function is non-negative for all n-qutrit stabilizer states and Clifford transformations. We also provide some evidence that extending the other sets of non-negative single-qubit states to multiple qubits does not give entangled states.
Anomaly-induced transport and thermodynamics

Kristan Jensen University of Victoria
November 13, 2012

PIRSA:12110047
Quantum Fields and Strings
I will discuss recent progress in the study of anomaly-induced transport, focusing on the chiral vortical effect in 3+1 dimensions. Most of my discussion will be framed in light of a larger story, namely progress in making exact statements about finite-temperature quantum field theory, for which the chiral magnetic and vortical effects are instructive prototypes.
Stealthy, Composite Stops

Philip Tanedo Cornell University
November 13, 2012

PIRSA:12110063
Particle Physics
Light third generation superpartners are one way to avoid bounds on new physics from the early LHC. We will review the theory and phenomenology of light stops and highlight a particular UV model based a partially composite electroweak sector through Seiberg duality.
Recent progress on de Sitter S-matrix

Ian Morrison West Chester University
November 13, 2012

PIRSA:12110043
Cosmology
The de Sitter S-matrix provides a gauge-invariant and field redefinition-invariant window into de Sitter QFTs and may provide a crucial entry in any dS/CFT dictionary. In this talk I will summarize recent progress on developing the S-matrix for theories with gauge fields and perturbative gravity. Nonrenormalization theorems, hints of supersymmetry, and perturbative stability will be discussed.
Statistical Mechanics - Lecture 2

John Berlinsky McMaster University

November 13, 2012

PIRSA:12110020
Quantum Field Theory 2 - Lecture 2

Francois David CEA Saclay
November 13, 2012

PIRSA:12110001
Quantum Fields and Strings
Statistical Mechanics - Lecture 1

John Berlinsky McMaster University

November 12, 2012

PIRSA:12110019
Quantum Field Theory 2 - Lecture 1

Francois David CEA Saclay
November 12, 2012

PIRSA:12110000
Quantum Fields and Strings
Geometric algebra techniques in flux compactifications

Calin Lazaroiu Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering
November 09, 2012

PIRSA:12110058
Mathematical physics
Using techniques originating in a certain approach to Clifford bundles known as "geometric algebra", I discuss a geometric reformulation of constrained generalized Killing spinor equations which proves to be particularly effective in the study and classification of supersymmetric flux compactifications of string and M-theory. As an application, I discuss the most general N=2 compactifications of M-theory to three dimensions, which were never studied in full generality before. I also touch upon the connection of such techniques with a certain variant of the quantization of spin systems.
Dynamical evaporation of quantum horizons
November 08, 2012

PIRSA:12110064
Quantum Gravity
We describe of the evaporation process as driven by the dynamical evolution of the quantum gravitational degrees of freedom resident at the horizon, as identified by the Loop Quantum Gravity kinematics. Using a parallel with the Brownian motion, we interpret the first law of quantum dynamical horizon in terms of a fluctuation-dissipation relation applied to this fundamental discrete structure. In this way, the horizon evolution is described in terms of relaxation to an equilibrium state balanced by the excitation of Planck scale constituents of the horizon. We show how from this setting the emergence of several conservative scenarios for the final stage of the evaporation process can be microscopically derived. Namely, the leakage of part of the horizon quantum geometry information prior to the Planckian phase and the stabilization of the hole surface shrinkage forming a massive remnant, which can eventually decay, are shown to take place.
Discovery of the Higgs Boson: Sweet Dream or Nightmare

Melissa Franklin Harvard University

November 07, 2012

PIRSA:12110055
Optimal quantum self-tests based on binary nonlocal XOR games

November 07, 2012

PIRSA:12110067

Self-testing a multipartite quantum state means verifying the existence of the state based on the outcomes of unknown or untrusted measurements. This concept is important in device-independent quantum cryptography. There are some previously known results on self-testing which involve nonlocal binary XOR games such as the CHSH test and the GHZ paradox. In our work we expand on these results. We provide a general criterion which, when satisfied, guarantees that a given nonlocal binary XOR game is a robust self-test. The error term in this result is quadratic, which is the best possible. In my talk I will explain the conceptual basis for the criterion and offer some examples. This is joint work with Yaoyun Shi (arXiv:1207.1819).

Title	Date	Collection	Type	Info
Quasiprobability representations of qubits	2012‑11‑13	Quantum Foundations	Scientific Series	View details
Anomaly-induced transport and thermodynamics	2012‑11‑13	Quantum Fields and Strings	Scientific Series	View details
Stealthy, Composite Stops	2012‑11‑13	Particle Physics	Scientific Series	View details
Recent progress on de Sitter S-matrix	2012‑11‑13	Cosmology and Gravitation	Scientific Series	View details
Statistical Mechanics - Lecture 2	2012‑11‑13	12/13 PSI - Statistical Mechanics	Course	View details
Quantum Field Theory 2 - Lecture 2	2012‑11‑13	12/13 PSI - Quantum Field Theory 2	Course	View details
Statistical Mechanics - Lecture 1	2012‑11‑12	12/13 PSI - Statistical Mechanics	Course	View details
Quantum Field Theory 2 - Lecture 1	2012‑11‑12	12/13 PSI - Quantum Field Theory 2	Course	View details
Geometric algebra techniques in flux compactifications	2012‑11‑09	Strings Group Meeting	Scientific Series	View details
Dynamical evaporation of quantum horizons	2012‑11‑08	Quantum Gravity	Scientific Series	View details
Discovery of the Higgs Boson: Sweet Dream or Nightmare	2012‑11‑07	Public Lecture Series	Public Lectures	View details
Optimal quantum self-tests based on binary nonlocal XOR games	2012‑11‑07	Quantum Information	Scientific Series	View details

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