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Developing tools for bridging the gap between cold gases and materials

Applicant Pollet Lode
Number 131892
Funding scheme Ambizione
Research institution Institut für Theoretische Physik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Condensed Matter Physics
Start/End 01.10.2010 - 30.09.2011
Approved amount 117'456.00
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All Disciplines (2)

Discipline
Condensed Matter Physics
Theoretical Physics

Keywords (7)

ultracold atoms; quantum Monte Carlo simulations; Hubbard model; quantum magnetism; polarons; supersolidity; Helium-4

Lay Summary (English)

Lead
Lay summary
Ultracold atoms in an optical lattice can realize many prototypical models in condensed matter physics. Many of those models, like the Hubbard model, cannot be solved by numerical means. A fresh approach is to try to use the optical lattice system as a quantum simulator for such models, which could tell us to what degree the real material is described by the model. Previously, we worked hard on the validation phase of this quantum simulator, and we could show that the simulator produces the correct answers not only for the Bose-Hubbard model, but also for the Fermi-Hubbard model at the presently relevant temperatures. However, it also became clear that effects such as spontaneous emission, atom losses, laser noise, collisions with background atoms, equilibration and (re)thermalization times become important in present state-of-the-art experiments, and the next generation of experiments will have to improve on these issues. In this proposal, we suggest to continue our quantitative analysis of cold gases. We will closely follow the experimental developments in the systems that we have studied before, but we will also extend our analysis to a variety of other contexts:

1. Bose-Hubbard model, where single site resolution offers new possibilities for criticality and thermometry. 2. Fermi-Hubbard model, where the thermodynamics for temperatures approaching the Neel temperature will be determined 3. Impurities in cold gases (polaron models). We would like to study polaron physics in a variety of contexts, such as an impurity in a Bose-Einstein condensate or impurities in the presence of a multi-component fermionic system. Both static and itinerant impurities, and both continuous and lattice models are of interest. 4. Mixtures and imbalanced systems. We will study when and how they can be understood as a system of interating polarons. 5. Disordered fermions. Experiments on Anderson localization in one dimension were done with cold gases recently, but in three dimensions questions remain. 6. Supersolids. The study of long-range interactions remains difficult in numerical studies, but experimental progress with molecules and Rydberg atoms opens new perspectives for experiments.

We also would like to initiate the next step in this program, which is working toward a better understanding of materials, through exploring two recent alogrithmic developments:

1. diagrammatic Monte Carlo applied to the electron gas problem and simple metals 2. tensor network states in combination with stochastic methods in order to study frustrated spin models.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Competition between Pairing and Ferromagnetic Instabilities in Ultracold Fermi Gases near Feshbach Resonances
Pekker D, Babadi M, Sensarma R, Zinner N, Pollet L, Zwierlein MW, Demler E (2011), Competition between Pairing and Ferromagnetic Instabilities in Ultracold Fermi Gases near Feshbach Resonances, in PHYSICAL REVIEW LETTERS, 106(5), 050402-050405.
Dynamical mean-field theory for bosons
Anders P, Gull E, Pollet L, Troyer M, Werner P (2011), Dynamical mean-field theory for bosons, in NEW JOURNAL OF PHYSICS, 13, 075013-075038.
Incorporating dynamic mean-field theory into diagrammatic Monte Carlo
Pollet L, Prokof'ev NV, Svistunov BV (2011), Incorporating dynamic mean-field theory into diagrammatic Monte Carlo, in PHYSICAL REVIEW B, 83(16), 161103-161106.
Localization of Toric Code Defects
Stark C, Pollet L, Imamoglu A, Renner R (2011), Localization of Toric Code Defects, in PHYSICAL REVIEW LETTERS, 107(3), 030504-030507.
The ALPS project release 2.0: open source software for strongly correlated systems
Bauer B, Carr LD, Evertz HG, Feiguin A, Freire J, Fuchs S, Gamper L, Gukelberger J, Gull E, Guertler S, Hehn A, Igarashi R, Isakov SV, Koop D, Ma PN, Mates P, Matsuo H, Parcollet O, Pawlowski G, Picon JD, Pollet L, Santos E, Scarola VW, Schollwoeck U, Silva C (2011), The ALPS project release 2.0: open source software for strongly correlated systems, in JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT, 2011, 05001-05018.
Thermodynamics of the 3D Hubbard Model on Approaching the Neel Transition
Fuchs S, Gull E, Pollet L, Burovski E, Kozik E, Pruschke T, Troyer M (2011), Thermodynamics of the 3D Hubbard Model on Approaching the Neel Transition, in PHYSICAL REVIEW LETTERS, 106(3), 030401-030404.
Comment on "Direct Mapping of the Finite Temperature Phase Diagram of Strongly Correlated Quantum Models"
Pollet L, Prokof'ev N, Svistunov B (2010), Comment on "Direct Mapping of the Finite Temperature Phase Diagram of Strongly Correlated Quantum Models", in PHYSICAL REVIEW LETTERS, 105(19), 199601-199601.
Observation of Correlated Particle-Hole Pairs and String Order in Low-Dimensional Mott Insulators
Endres M, Cheneau M, Fukuhara T, Weitenberg C, Schauss P, Gross C, Mazza L, Banuls M.C., Pollet L, Bloch I, Kuhr S, Observation of Correlated Particle-Hole Pairs and String Order in Low-Dimensional Mott Insulators, in Science.

Collaboration

Group / person Country
Types of collaboration
LMU Munich Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
University of Massachusetts at Amherst United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Swiss-Japanese meeting Talk given at a conference Developing bosonic dynamical mean-field theory 16.09.2011 ETH Zurich, Switzerland Pollet Lode;
BEC2011 Talk given at a conference Developing new Monte Carlo approaches for cold gases 11.09.2011 San Feliu, Spain, Spain Pollet Lode;
APS DAMOP meeting Talk given at a conference A quantitative analysis of atomic and molecular systems 13.06.2011 Altanta, GA, USA, United States of America Pollet Lode;
Supersolidity 2011 Talk given at a conference Structural and superfluid properties of solid He-4 in confined media 06.06.2011 CUNY, New York City, USA, United States of America Pollet Lode;
International Conference on cold gases Talk given at a conference Thermodynamics of the 3D Hubbard model on approach to the Neel transition 03.04.2011 Tegernsee, Germany, Germany Pollet Lode;
APS March Meeting Talk given at a conference A quantitative analysis of ultracold atoms in an optical lattice 21.03.2011 Dallas, TX, USA, United States of America Pollet Lode;
PIRE meeting Talk given at a conference Ultracold fermions in an optical lattice 07.01.2011 Wuerzburg, Germany, Germany Pollet Lode;
BOPTILATT10 and COMPQMC10, KITP Santa Barbara Talk given at a conference Developing the bosonic DMFT formalism 11.10.2010 Santa Barbara, CA, USA, United States of America Pollet Lode;


Communication with the public

Communication Title Media Place Year
New media (web, blogs, podcasts, news feeds etc.) Quanteninformationen dauerhaft speichern ETH life German-speaking Switzerland 2011

Associated projects

Number Title Start Funding scheme
124157 A quantitative analysis of ultracold atoms in an optical lattice 01.04.2009 Fellowships for advanced researchers

Abstract

In this grant application we propose to continue our research on cold gases in an optical lattice. We would like to understand them quantitatively better in a variety of contexts:- Hubbard type of models- polaron models and disordered modelsThis will be done with a combination of analytical and numerical (Monte Carlo) methods.We would also like to know what those models can tell us about real materials, by exploring 2 new algorithmic advances:- Diagrammatic Monte Carlo will be used for the study of higher order corrections to the GW method- we will apply Monte Carlo methods in the context of tensor network states, which could offer new opportunities to study frustrated magnetism.
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