Quantum Matter

434 talks

S021

Collection TypeSeries

Source RepositoryPIRSA

Displaying 313 - 324 of 434

TBA
July 08, 2014

PIRSA:14070018
Condensed Matter
Phenomenology of charge order in underdoped cuprates

Andrea Allais Harvard University

May 27, 2014

PIRSA:14050147
Designing exotic circuitry with non-Abelian anyons
May 20, 2014

PIRSA:14050029
Condensed Matter
Bulk-Edge Correspondence in 2+1-Dimensional Abelian Topological Phases

Jennifer Cano University of California System
May 09, 2014

PIRSA:14050011
Condensed Matter
Scattering of emerging excitations in Matrix Product States

Jutho Haegeman Ghent University
May 06, 2014

PIRSA:14050010
Condensed Matter
Helical edge resistance introduced by charge disorder

Leonid Glazman Yale University
April 29, 2014

PIRSA:14040082
Condensed Matter
TBA

Eun-Gook Moon Korea Advanced Institute of Science and Technology (KAIST)

April 25, 2014

PIRSA:14040142
Quantum criticality in SU(N) anti-ferromagnets: general strategies to circumvent the sign problem

Ribhu Kaul University of Kentucky
April 22, 2014

PIRSA:14040083
Condensed Matter
The unitary Fermi gas across the superfluid transition

Olga Goulko University of Massachusetts Amherst
April 04, 2014

PIRSA:14040119
Condensed Matter
Fibonacci Anyons From Abelian Bilayer Quantum Hall States

Abolhassan Vaezi Cornell University
April 01, 2014

PIRSA:14040120
Condensed Matter
Are superselection rules fundamental?

Robert Spekkens Perimeter Institute for Theoretical Physics
March 14, 2014

PIRSA:14030114
Condensed Matter
DMRG Analysis of Mobile Impurities and Orbital-selective Mott Phases

Julian (Jose) Rincon Universidad de los Andes
March 12, 2014

PIRSA:14030117
Condensed Matter

TBA
July 08, 2014

PIRSA:14070018
Condensed Matter
Phenomenology of charge order in underdoped cuprates

Andrea Allais Harvard University

May 27, 2014

PIRSA:14050147

In the past few years substantial evidence has been collected that points to coexistence of charge correlations with long range superconductivity in underdoped cuprate superconductors. In this talk I will review some of this evidence, then show that a charge density wave with precisely the same signatures is a natural instability of an antiferromagnetic metal, and finally derive some phenomenological consequences, with special focus on quantum oscillation experiments.
Designing exotic circuitry with non-Abelian anyons
May 20, 2014

PIRSA:14050029
Condensed Matter
Non-Abelian anyons are widely sought for the exotic fundamental physics they harbor as well as for their possible applications for quantum information processing. Currently, there are numerous blueprints for stabilizing the simplest type of non-Abelian anyon, a Majorana zero energy mode bound to a vortex or a domain wall. One such candidate system, a so-called "Majorana wire" can be made by judiciously interfacing readily available materials; the experimental evidence for the viability of this approach is presently emerging.
Following this idea, we introduce a device fabricated from conventional fractional quantum Hall states, s-wave superconductors and insulators with strong spin-orbit coupling. Similarly to a Majorana wire, the ends of our “quantum wire” would bind "parafermions", exotic non-Abelian anyons which can be viewed as fractionalised Majorana zero modes.
I will discuss their properties and describe how such parafermions can be used to construct new and potentially useful circuit elements which include current and voltage mirrors, transistors for fractional charge currents and "flux capacitors".
Bulk-Edge Correspondence in 2+1-Dimensional Abelian Topological Phases

Jennifer Cano University of California System
May 09, 2014

PIRSA:14050011
Condensed Matter
The same bulk two-dimensional topological phase can have multiple distinct, fully-chiral edge phases. We show that this can occur in the integer quantum Hall states at fillings 8 and 12 with experimentally-testable consequences. We also show examples for Abelian fractional quantum Hall states, the simplest examples being at filling fractions 8/7, 12/11, 8/15, 16/5. For all examples, we propose experiments that can distinguish distinct edge phases. Our results are summarized by the observation that edge phases correspond to lattices while bulk phases correspond to genera of lattices. Since there are typically multiple lattices in a genus, there are usually many stable fully chiral edge phases corresponding to the same bulk. We show that fermionic systems can have edge phases with only bosonic low-energy excitations and discuss a fermionic generalization of the relation between bulk topological spins and the central charge. The latter follows from our demonstration that every fermionic topological phase can be represented as a bosonic topological phase, together with some number of filled Landau levels. Our analysis also leads to a simple demonstration that all Abelian topological phases can be represented by a Chern-Simons theory parameterized by a K-matrix.
Scattering of emerging excitations in Matrix Product States

Jutho Haegeman Ghent University
May 06, 2014

PIRSA:14050010
Condensed Matter
We review the formalism of matrix product states and one of its recent generalisations which allows to variationally determine the dispersion relation of elementary excitations in generic one-dimensional quantum spin chains. These elementary excitations dominate the low energy effective behaviour of the system. We discuss recent work where we show how we can also describe the effective interaction between these excitations – as mediated by the strongly correlated ground state – and how we can extract the corresponding S matrix. With these two ingredients, we can already build a highly non-trivial low-energy description of any microscopic Hamiltonian by assuming that higher order scattering processes are negligible. This allows to extract accurate information about the behaviour of the system under perturbations or at finite temperature, as we illustrate using the spin 1 Heisenberg model.
Helical edge resistance introduced by charge disorder

Leonid Glazman Yale University
April 29, 2014

PIRSA:14040082
Condensed Matter
Electron puddles created by doping of a 2D topological insulator may violate the ideal helical edge conductance. Because of a long electron dwelling time, even a single puddle may lead to a significant inelastic backscattering. We find the resulting correction to the perfect edge conductance. Generalizing to multiple puddles, we assess the dependence of the helical edge resistance on temperature and on the doping level. Puddles with odd electron number carry a spin and lead to a logarithmically-weak temperature dependence of the resistivity of a long edge. The developed theory provides a framework for analyzing the results of the past and ongoing electron transport experiments with 2D topological insulators
TBA

Eun-Gook Moon Korea Advanced Institute of Science and Technology (KAIST)

April 25, 2014

PIRSA:14040142
Quantum criticality in SU(N) anti-ferromagnets: general strategies to circumvent the sign problem

Ribhu Kaul University of Kentucky
April 22, 2014

PIRSA:14040083
Condensed Matter
In the first part of the seminar, I will describe a general approach to write down a large family of model SU(N) anti-ferromagnets that do not suffer from the sign problem. In the second half I will show how such Hamiltonians are useful for the study of deconfined quantum critical points and possibly other exotic physics.
The unitary Fermi gas across the superfluid transition

Olga Goulko University of Massachusetts Amherst
April 04, 2014

PIRSA:14040119
Condensed Matter
Quantum Monte Carlo is a versatile tool for studying strongly interacting theories in condensed matter physics from first principles. A prominent example is the unitary Fermi gas: a two-component system of fermions interacting with divergent scattering length. I will present numerical results for different properties of the homogeneous, spin-balanced unitary Fermi gas across the superfluid transition, such as the critical temperature, the equation of state and the temperature dependence of the contact density. Our values show good agreement with recent experimental data.
Fibonacci Anyons From Abelian Bilayer Quantum Hall States

Abolhassan Vaezi Cornell University
April 01, 2014

PIRSA:14040120
Condensed Matter
The possibility of realizing non-Abelian statistics and utilizing it for topological quantum computation (TQC) has generated widespread interest. However, the non-Abelian statistics that can be realized in most accessible proposals is not powerful enough for universal TQC. In this talk, I consider a simple bilayer fractional quantum Hall (FQH) system with the 1/3 Laughlin state in each layer, in the presence of interlayer tunneling. I show that interlayer tunneling can drive a continuous phase transition to an exotic non-Abelian state that contains the famous `Fibonacci' anyon, whose non-Abelian statistics is powerful enough for universal TQC. The analysis that I will present towards this result rests on startling agreements from a variety of distinct methods, including thin torus limits, effective field theories, and coupled wire constructions.

Next, I discuss the experimental aspects of our proposal and potential probes for the Fibonacci phase. I show that the charge gap remains open at the phase transition while the neutral gap closes. This raises the question of whether these exotic phases may have already been realized at nu=2/3 in bilayers, as past experiments may not have definitively ruled them out. Finally, I will discuss about the generalizations to multi-layer states as well as the duality between the interlayer pairing and interlayer tunneling problems.

Reference: arXiv:1403.3383
Are superselection rules fundamental?

Robert Spekkens Perimeter Institute for Theoretical Physics
March 14, 2014

PIRSA:14030114
Condensed Matter
Superselection rules in quantum theory assert the impossibility of preparing coherent superpositions of certain conserved quantities. For instance, it is commonly presumed that there is a superselection rule for charge and for baryon number, as well as a "univalence superselection rule" forbidding a coherent superposition of a fermion and a boson. I will show how many superselection rules can be effectively lifted using a reference frame for the variable that is conjugate to the conserved quantity. I will also discuss subtleties related to the univalence superselection rule.
DMRG Analysis of Mobile Impurities and Orbital-selective Mott Phases

Julian (Jose) Rincon Universidad de los Andes
March 12, 2014

PIRSA:14030117
Condensed Matter

Title	Speaker(s)	Date	Talk Type	Info
TBA		2014-07-08	Scientific Series	View details
Phenomenology of charge order in underdoped cuprates	Andrea Allais	2014-05-27	Scientific Series	View details
Designing exotic circuitry with non-Abelian anyons		2014-05-20	Scientific Series	View details
Bulk-Edge Correspondence in 2+1-Dimensional Abelian Topological Phases	Jennifer Cano	2014-05-09	Scientific Series	View details
Scattering of emerging excitations in Matrix Product States	Jutho Haegeman	2014-05-06	Scientific Series	View details
Helical edge resistance introduced by charge disorder	Leonid Glazman	2014-04-29	Scientific Series	View details
TBA	Eun-Gook Moon	2014-04-25	Scientific Series	View details
Quantum criticality in SU(N) anti-ferromagnets: general strategies to circumvent the sign problem	Ribhu Kaul	2014-04-22	Scientific Series	View details
The unitary Fermi gas across the superfluid transition	Olga Goulko	2014-04-04	Scientific Series	View details
Fibonacci Anyons From Abelian Bilayer Quantum Hall States	Abolhassan Vaezi	2014-04-01	Scientific Series	View details
Are superselection rules fundamental?	Robert Spekkens	2014-03-14	Scientific Series	View details
DMRG Analysis of Mobile Impurities and Orbital-selective Mott Phases	Julian (Jose) Rincon	2014-03-12	Scientific Series	View details

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Format results

TBA

Phenomenology of charge order in underdoped cuprates

Designing exotic circuitry with non-Abelian anyons

Bulk-Edge Correspondence in 2+1-Dimensional Abelian Topological Phases

Scattering of emerging excitations in Matrix Product States

Helical edge resistance introduced by charge disorder

TBA

Quantum criticality in SU(N) anti-ferromagnets: general strategies to circumvent the sign problem

The unitary Fermi gas across the superfluid transition

Fibonacci Anyons From Abelian Bilayer Quantum Hall States

Are superselection rules fundamental?

DMRG Analysis of Mobile Impurities and Orbital-selective Mott Phases

TBA

Phenomenology of charge order in underdoped cuprates

Designing exotic circuitry with non-Abelian anyons

Bulk-Edge Correspondence in 2+1-Dimensional Abelian Topological Phases

Scattering of emerging excitations in Matrix Product States

Helical edge resistance introduced by charge disorder

TBA

Quantum criticality in SU(N) anti-ferromagnets: general strategies to circumvent the sign problem

The unitary Fermi gas across the superfluid transition

Fibonacci Anyons From Abelian Bilayer Quantum Hall States

Are superselection rules fundamental?

DMRG Analysis of Mobile Impurities and Orbital-selective Mott Phases