Quantum Matter

Displaying 313 - 324 of 439

Monogamy of entanglement and improved mean-field ansatz for spin lattices

Ralf Schuetzhold Helmholtz-Zentrum Dresden-Rossendorf
September 02, 2014

PIRSA:14090069
Condensed Matter
TBA

Senthil Todadri Massachusetts Institute of Technology (MIT) - Department of Physics
August 19, 2014

PIRSA:14080036
Condensed Matter
Reconstructing quantum states from local data

Isaac Kim University of California, Davis
August 12, 2014

PIRSA:14080007
Condensed Matter
Criterion for non-Fermi Liquid behavior in a metal with broken symmetry

Ashvin Vishwanath Harvard University
August 06, 2014

PIRSA:14080004
Condensed Matter
Uni10 Tensor Network Library

Ying-Jer Kao National Taiwan University
August 05, 2014

PIRSA:14080001
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
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, Santa Barbara
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

Monogamy of entanglement and improved mean-field ansatz for spin lattices

Ralf Schuetzhold Helmholtz-Zentrum Dresden-Rossendorf
September 02, 2014

PIRSA:14090069
Condensed Matter
We consider rather general spin-1/2 lattices with large coordination numbers Z.
Based on the monogamy of entanglement and other properties of the concurrence C,
we derive rigorous bounds for the entanglement between neighboring spins,
which show that C decreases for large Z. In addition, the concurrence C measures the deviation from mean-field behavior and can only vanish if the mean-field ansatz yields an exact ground state of the Hamiltonian. Motivated by these findings, we propose an improved mean-field ansatz by adding entanglement
TBA

Senthil Todadri Massachusetts Institute of Technology (MIT) - Department of Physics
August 19, 2014

PIRSA:14080036
Condensed Matter
Reconstructing quantum states from local data

Isaac Kim University of California, Davis
August 12, 2014

PIRSA:14080007
Condensed Matter
We consider the problem of reconstructing global quantum states from local data. Because the reconstruction problem has many solutions in general, we consider the reconstructed state of maximum global entropy consistent with the local data. We show that unique ground states of local Hamiltonians are exactly reconstructed as the maximal entropy state. More generally, we show that if the state in question is a ground state of a local Hamiltonian with a degenerate space of locally indistinguishable ground states, then the maximal entropy state is close to the ground state projector. We also show that local reconstruction is possible for thermal states of local Hamiltonians. Finally, we discuss a procedure to certify that the reconstructed state is close to the true global state. We call the entropy of our reconstructed maximum entropy state the "reconstruction entropy", and we discuss its relation to emergent geometry in the context of holographic duality. This is a joint work with Brian Swingle.
Criterion for non-Fermi Liquid behavior in a metal with broken symmetry

Ashvin Vishwanath Harvard University
August 06, 2014

PIRSA:14080004
Condensed Matter
Uni10 Tensor Network Library

Ying-Jer Kao National Taiwan University
August 05, 2014

PIRSA:14080001
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, Santa Barbara
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

Title	Speaker(s)	Date	Talk Type	Info
Monogamy of entanglement and improved mean-field ansatz for spin lattices	Ralf Schuetzhold	2014-09-02	Scientific Series	View details
TBA	Senthil Todadri	2014-08-19	Scientific Series	View details
Reconstructing quantum states from local data	Isaac Kim	2014-08-12	Scientific Series	View details
Criterion for non-Fermi Liquid behavior in a metal with broken symmetry	Ashvin Vishwanath	2014-08-06	Scientific Series	View details
Uni10 Tensor Network Library	Ying-Jer Kao	2014-08-05	Other	View details
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 Matter

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