Talks

11077 - 11088 of 18366 Results

Fractional quantum Hall effect and tunable interactions

Zlatko Papic University of Leeds

November 29, 2012

PIRSA:12110081

Condensed Matter
Fractional Chern Insulators

Titus Neupert ETH Zurich

November 29, 2012

PIRSA:12110080

Condensed Matter
Statistical Mechanics - Lecture 14

John Berlinsky McMaster University

November 29, 2012

PIRSA:12110036
Quantum Field Theory 2 - Lecture 14

Francois David CEA Saclay

November 29, 2012

PIRSA:12110017

High Energy Physics
Dyon condensation in topological Mott insulators

Gil Young Cho Pohang University of Science and Technology

November 28, 2012

PIRSA:12110087

Condensed Matter
Wiring up Quantum Systems: Fun with Artificial Atoms and Microwave Photons

Steve Girvin Yale University

November 28, 2012

PIRSA:12110041

Condensed Matter
12/13 PSI Researcher Presentation

Steve Girvin Yale University

November 28, 2012

PIRSA:12110093

Condensed Matter
Statistical Mechanics - Lecture 13

John Berlinsky McMaster University

November 28, 2012

PIRSA:12110035
Chern-Simons Contact Terms

Thomas Dumitrescu University of California, Los Angeles

November 28, 2012

PIRSA:12110094

High Energy Physics
Quantum Field Theory 2 - Lecture 13

Francois David CEA Saclay

November 28, 2012

PIRSA:12110016

High Energy Physics
Entanglement and the Fermi surface

Brian Swingle Brandeis University

November 27, 2012

PIRSA:12110082

Condensed Matter
Exact Calculations in the 1D Continuum for DFT and Beyond

November 27, 2012

PIRSA:12110085

Fractional quantum Hall effect and tunable interactions

Zlatko Papic University of Leeds

November 29, 2012

PIRSA:12110081

Condensed Matter

In this talk I will review some existing experimental methods, as well as a few recent theoretical proposals, to tune the interactions in a number of low-dimensional systems exhibiting the fractional quantum Hall effect (FQHE). The materials in question include GaAs wide quantum wells and multilayer graphene, where the tunability of the electron-electron interactions can be achieved via modifying the band structure, dielectric environment of the sample, by tilting the magnetic field or varying the mass tensor, and by mixing of electronic subbands and Landau levels. Because the interesting topological (and in particular, non-Abelian) states arise solely due to strong interactions, the ability to tune them is essential for ``designing" more robust FQHE states. Furthermore, I will argue that some of these mechanisms can also be used to probe the subtle aspects of FQHE physics, such as the breaking of particle-hole symmetry between the Moore-Read Pfaffian and anti-Pfaffian states, and the transition between FQHE fluids and broken-symmetry states due to the fluctuation of the intrinsic geometric degree of freedom.
Fractional Chern Insulators

Titus Neupert ETH Zurich

November 29, 2012

PIRSA:12110080

Condensed Matter

Fractional Chern insulators (FCIs) are topologically ordered states of interacting fermions that share their universal properties with fractional quantum Hall states in Landau levels. FCIs have been found numerically in a variety of two-dimensional lattice models upon partially filling an almost dispersionless band with nontrivial topological character with repulsively interacting fermions. I will show how FCIs emerge in bands with Chern number C=1 and C=2 and in Z_2 topological insulators, where the latter are accompanied by a spontaneous breaking of time-reversal symmetry. Further, I will discuss the relevance of the noncommutative quantum geometry of the flat topological band to the stability of FCIs and how they can be distinguished from phases of spontaneously broken point group symmetry, such as charge density waves.
Statistical Mechanics - Lecture 14

John Berlinsky McMaster University

November 29, 2012

PIRSA:12110036
Quantum Field Theory 2 - Lecture 14

Francois David CEA Saclay

November 29, 2012

PIRSA:12110017

High Energy Physics
Dyon condensation in topological Mott insulators

Gil Young Cho Pohang University of Science and Technology

November 28, 2012

PIRSA:12110087

Condensed Matter

We consider quantum phase transitions out of topological Mott insulators in which the ground state of the fractionalized excitations (fermionic spinons) is topologically non-trivial. The spinons in topological Mott insulators are coupled to an emergent compact U(1) gauge field with a so-called "axion" term. We study the confinement transitions from the topological Mott insulator to broken symmetry phases, which may occur via the condensation of dyons. Dyons carry both "electric" and "magnetic" charges, and arise naturally in this system because the monopoles of the emergent U(1) gauge theory acquires gauge charge due to the axion term. It is shown that the dyon condensate, in general, induces simultaneous current and bond orders. When the magnetic transition is driven by dyon condensation, we identify the bond order as valence bond solid order and the current order as scalar spin chirality order. Hence, the confined phase of the topological Mott insulator is an exotic phase where the scalar spin chirality and the valence bond order coexist and appear via a single transition. If time allows, I will also discuss our recent work on the proximate symmetry-broken phases of Z2 spin liquid on Kagome lattice.
Wiring up Quantum Systems: Fun with Artificial Atoms and Microwave Photons

Steve Girvin Yale University

November 28, 2012

PIRSA:12110041

Condensed Matter

A revolution is underway in the construction of ‘artificial atoms’ out of superconducting electrical circuits. These macroscopic ‘atoms’ have quantized energy levels and can emit and absorb quanta of light (in this case microwave photons), just like ordinary atoms. Unlike ‘real’ atoms, the properties of these artificial atoms can be engineered to suit various particular applications, and they can be connected together by wires to form quantum ‘computer chips.’ This so-called ‘circuit QED’ architecture has given us the ability to do non-linear quantum optics in electrical circuits at the single photon level. It is now possible to entangle multiple qubits, count individual microwave photons, create large ‘Schrödinger cat’ photon states and perform quantum feedback. This talk will present an elementary introduction to the field.
12/13 PSI Researcher Presentation

Steve Girvin Yale University

November 28, 2012

PIRSA:12110093

Condensed Matter
Statistical Mechanics - Lecture 13

John Berlinsky McMaster University

November 28, 2012

PIRSA:12110035
Chern-Simons Contact Terms

Thomas Dumitrescu University of California, Los Angeles

November 28, 2012

PIRSA:12110094

High Energy Physics

Chern-Simons contact terms constitute new observables in three-dimensional quantum field theory. In N=2 supersymmetric theories with an R-symmetry, they lead to a superconformal anomaly. This understanding clarifies several puzzles surrounding the S3 partition function of these theories. In particular, it leads to a proof of the F-maximization principle. Chern-Simons contact terms can be computed exactly using localization and lead to new tests of proposed dualities.
Quantum Field Theory 2 - Lecture 13

Francois David CEA Saclay

November 28, 2012

PIRSA:12110016

High Energy Physics
Entanglement and the Fermi surface

Brian Swingle Brandeis University

November 27, 2012

PIRSA:12110082

Condensed Matter

In this talk I will describe my work characterizing quantum entanglement in systems with a Fermi surface. This class includes everything from Fermi liquids to exotic spin liquids in frustrated magnets and perhaps even holographic systems. I review my original scaling argument and then describe in detail a number of new precise results on entanglement in Fermi liquids. I will also discuss recent quantum Monte Carlo calculations of Renyi entropies and will argue that we now have a rather complete agreement between theory and numerics for Fermi liquid entanglement. I will also discuss universal crossovers between thermal and entanglement entropy and a class of solvable interacting models where we can prove the universality of the Widom formula for Fermi surface entanglement. If there is time, I will comment on several other topics including fluctuations of conserved quantities and connections to holography.
Exact Calculations in the 1D Continuum for DFT and Beyond

November 27, 2012

PIRSA:12110085

Most applications of the density matrix renormalization group (DMRG) have been to lattice models with short range interactions. But recent developments in DMRG technology open the door to studying continuum systems with long-range interactions in one dimension (1d). One key motivation is simulating cold atom experiments, where it is possible to engineer Hamiltonians of precisely this type. We have been applying DMRG in the 1d continuum with another motivation: to investigate and improve density functional theory (DFT). DFT has exact mathematical foundations, but in practice one must use approximations. These approximations work incredibly well for weakly correlated systems yet fail when correlations are strong. Improving DFT directly for realistic 3d systems is hard because few systems can be solved exactly. By working in the 1d continuum instead, we can use the power of DMRG to study DFT. We can implement both the exact DFT formalism and standard DFT approximations. After showing how to overcome the challenges in performing these calculations, I will discuss some of the key questions we are investigating, for example, the ability of DFT to predict gaps of insulating systems.

Title	Date	Collection	Type	Info
Fractional quantum Hall effect and tunable interactions	2012‑11‑29	Quantum Matter	Scientific Series	View details
Fractional Chern Insulators	2012‑11‑29	Quantum Matter	Scientific Series	View details
Statistical Mechanics - Lecture 14	2012‑11‑29	12/13 PSI - Statistical Mechanics	Course	View details
Quantum Field Theory 2 - Lecture 14	2012‑11‑29	12/13 PSI - Quantum Field Theory 2	Course	View details
Dyon condensation in topological Mott insulators	2012‑11‑28	Quantum Matter	Scientific Series	View details
Wiring up Quantum Systems: Fun with Artificial Atoms and Microwave Photons	2012‑11‑28	Colloquium	Scientific Series	View details
12/13 PSI Researcher Presentation	2012‑11‑28	12/13 PSI Researcher Presentations	Course	View details
Statistical Mechanics - Lecture 13	2012‑11‑28	12/13 PSI - Statistical Mechanics	Course	View details
Chern-Simons Contact Terms	2012‑11‑28	Quantum Fields and Strings	Scientific Series	View details
Quantum Field Theory 2 - Lecture 13	2012‑11‑28	12/13 PSI - Quantum Field Theory 2	Course	View details
Entanglement and the Fermi surface	2012‑11‑27	Quantum Matter	Scientific Series	View details
Exact Calculations in the 1D Continuum for DFT and Beyond	2012‑11‑27	Quantum Matter	Scientific Series	View details

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Format results

Fractional quantum Hall effect and tunable interactions

Fractional Chern Insulators

Statistical Mechanics - Lecture 14

Quantum Field Theory 2 - Lecture 14

Dyon condensation in topological Mott insulators

Wiring up Quantum Systems: Fun with Artificial Atoms and Microwave Photons

12/13 PSI Researcher Presentation

Statistical Mechanics - Lecture 13

Chern-Simons Contact Terms

Quantum Field Theory 2 - Lecture 13

Entanglement and the Fermi surface

Exact Calculations in the 1D Continuum for DFT and Beyond

Fractional quantum Hall effect and tunable interactions

Fractional Chern Insulators

Statistical Mechanics - Lecture 14

Quantum Field Theory 2 - Lecture 14

Dyon condensation in topological Mott insulators

Wiring up Quantum Systems: Fun with Artificial Atoms and Microwave Photons

12/13 PSI Researcher Presentation

Statistical Mechanics - Lecture 13

Chern-Simons Contact Terms

Quantum Field Theory 2 - Lecture 13

Entanglement and the Fermi surface

Exact Calculations in the 1D Continuum for DFT and Beyond