News from the Lab 2018

  • Dec. 19: Defensio (Dissertation) of Christian Romen "Numerical Investigation of exotic Mott Insulators" (Dissertation)
    At 11:00 | Room 2S17, ICT building | Everybody is welcome to join!
  • Dec. 17: Defensio (Master) of Sandro Huber "Analysis of holographic entanglement entropy and its underlying geometry"
    At 10:30 | Room 2S16, ICT building | Everybody is welcome to join!
  • Nov. 13, 10:30 "Large-scale numerical investigations of fermions coupled to critical bosons"
    Speaker: Prof. Zi Yang Meng | Location: ICT building, 1st floor, seminar room 2S17 | Abstract: In this talk, I will present recent developments in conceptual and technical aspects of large-scale numerical simulations of correlated electron systems, in particular in the new quantum Monte Carlo methods. Fresh results on itinerant quantum critical points, i.e. the critical phenomena arising from the strong coupling between Fermi surface and bosonic fluctuations will be discussed, as well as its extension to the situation of gauge fields coupled to matter fields, which is fundamentally connected to the understanding of deconfined quantum criticality. References: Phys. Rev. X 7, 031052 (2017); arXiv:1807.07574; arXiv:1808.08878. Everybody is welcome to join!
  • Nov. 12 - Nov. 13: Zi Yang Meng, Institute of Physics, Chinese Academy of Sciences, Beijing
    We are happy to welcome our guest Prof. Meng from China!
  • Nov. 09: Defensio (Master) of Jonas Rigo "Artificial Neural Networks as Function Approximators in Quantum Many-Body Physics"
    At 10:00 | Room 2S16, ICT building | Everybody is welcome to join!
  • Oct. 16 - Oct. 18: Michael Scherer, University of Cologne, Germany
    Michael is visiting our group and gives a talk on Oct. 17th at 10:30 in the meeting room 2S16. Everybody is welcome to join!
  • Jun. 22: Quanten­welt: Infor­mations­aus­tausch braucht Zeit
    Die Quanteneigenschaften von Teilchen in Festkörpern können nur sehr schwierig untersucht werden. Quantensimulationen an künstlichen Systemen eröffnen völlig neue Möglichkeiten im Labor. Unter sehr gut kontrollierbaren Bedingungen können hier die Wechselwirkungen der einzelnen Teilchen in einem Vielteilchensystem sehr gut untersucht werden. Gemeinsam mit Experimentalphysikern der Universität Paris-Saclay haben Theoretiker um Andreas Läuchli vom Institut für Theoretische Physik der Universität Innsbruck nun die zeitliche und räumliche Ausbreitung von Quantenkorrelationen in zweidimensionalen Systemen aus Rubidium-Atomen beobachtet und quantitativ bestimmt. | Observing the Space- and Time-Dependent Growth of Correlations in Dynamically Tuned Synthetic Ising Models with Antiferromagnetic Interactions. Vincent Lienhard, Sylvain de Léséleuc, Daniel Barredo, Thierry Lahaye, Antoine Browaeys, Michael Schuler, Louis-Paul Henry, and Andreas M. Läuchli. Phys. Rev. X 8, 021070 (2018)
  • Jul. 11: Ian McCulloch, The University of Queensland, Australia
    Ian is visiting our group and gives a talk at 10:15 in the seminar room 2S17. Title: Topological states in frustrated magnets | Abstract: The triangular lattice is an archetype example of a frustrated lattice, that was conjectured by Phil Anderson many years ago to have a topologically ordered resonating valence bond ground-state. This appears to be realized in the J1-J2 heisenberg model on the triangular lattice, with an extended topologically ordered region in the vicinity of J2/J1=1/8. I will describe how translationally matrix product state calculations for an infinite cylinder can uncover most of the properties of properties of the topological phase using algebraic features such as the symmetries of the entanglement spectrum.
  • Jun. 14 at 15:00 in room 2S16: Group seminar talk by Alexander Seidel, Physics Department, Washington University in St. Louis
    Title: Entangled Pauli Principles: The DNA of Fractional Quantum Hall Fluids | Abstract: A major challenge in the study of strongly correlated electron systems is to establish a firm link between microscopic models and effective field theory. Quite often, this step involves a leap of faith, and/or extensive numerical studies. For fractional quantum Hall model wave functions, there exists — in some cases — a scheme to infer the long distance physics of the state that is both compelling and simple, and leaves very little room for ambiguity. This scheme involves a local parent Hamiltonian for the state, which unambiguously defines a "zero mode space" of elementary excitations, and what’s known as a "generalized Pauli principle", which efficiently organizes the zero mode space through one-dimensional patterns satisfying local rules. Where this works, universal properties of the state unambiguously emerge from counting exercises in terms of these patterns, which efficiently encode degeneracies, quasi-particle types and charges, and which completely determine an edge conformal field theory. There is even a natural scheme to infer braiding statistics directly, for both Abelian and non-Abelian states. Unfortunately, such a framework thus far exists for some quantum Hall states but not for others. In this talk, I will review the state of the art of this formalism, give reasons of why its "plain vanilla form" is insufficient to describe some important fractional quantum Hall states (e.g., Jain states), and explain how to address this deficiency through a new, more general concept, called "entangled Pauli principles". It will turn out that for some interesting quantum Hall states, the efficient description advertised here involves simple matrix-product-type entanglement. [1] arXiv:1803.00975. Everyone is welcome to attend!
  • Jun. 14: Alexander Seidel from the Washington University in St. Louis is visiting our group
  • May 15 at 10:30 in room 2S17: Group seminar talk by Charlotte Petersen, ITP Innsbruck
    Title: Investigating artificial spin ice through lattice design | Abstract: Artificial spin ice consists of interacting magnet subunits arranged on a two dimensional lattice. A key feature is the ability to precisely control the geometry, and so manufacture highly frustrated systems that are hindered to minimize their local interactions by lattice constraints. I present a new lattice geometry where the balance of competing interactions between nearest-neighbour moments can be directly controlled. This allows for tuning of the geometrical frustration. By varying the lattice parameters, we observe that the system either accesses a long-range ordered ground state, or under the same conditions, remains trapped in a disordered state with short-range correlations. Real time measurement in both this, and other lattice geometries, reveal that the presence of emergent magnetic charges are crucial to the dynamics. Investigating these defects in a lattice geometry with mixed coordination numbers we observe screening of the magnetic charges, reminiscent of electric charge screening, where reconfiguration of the local environment decreases the Coulomb interaction between charges. Through direct imaging of the real time creation and annihilation of these screened states, we determine that they form as a local energy reduction, as a transient towards the ground state. Everyone is welcome to attend!
  • May 02 at 15:30 in room 2S16: Group seminar talk by Martin Ganahl, PI
    Title: Some recent progress on continuous matrix product states | Abstract: Over the past several years, continuous Matrix Product States (cMPS) have emerged as a powerful tool for obtaining non-perturbative ground state and excited state properties of interacting quantum field theories (QFTs) in (1+1)d. At the heart of the cMPS lies an efficient parametrization of many-body wavefunctions directly in the continuum, that enables one to obtain ground states of QFTs in (1+1)d. In the first part of my talk I will give a short introduction to the cMPS formalism. In the second part, I will first discuss a new variational optimization method for cMPS. I will then explain how basis-spline expansions can be combined with a cMPS parametrization to obtain new results for systems without translational invariance, and how lattice MPS methods can be utilized within the framework of cMPS calculations. Everyone is welcome to attend!
  • May 02 - May 03: Martin Ganahl from Perimeter Institute, Waterloo, Canada is visiting our group
  • Apr. 24 at 10:30 in room 2S17: Group seminar talk by Vincenzo Alba, SISSA, Trieste
    Title: Entanglement and thermodynamics after a quantum quench in integrable systems | Abstract: Entanglement and entropy are key concepts standing at the foundations of quantum and statistical mechanics, respectively. In the last decade the study of quantum quenches revealed that these two concepts are intricately intertwined. Although the unitary time evolution ensuing from a pure initial state maintains the system globally at zero entropy, at long time after the quench local properties are captured by an appropriate statistical ensemble with non zero thermodynamic entropy, which can be interpreted as the entanglement accumulated during the dynamics. Therefore, understanding the post-quench entanglement evolution unveils how thermodynamics emerges in isolated quantum systems. An exact computation of the entanglement dynamics has been provided only for non-interacting systems, and it was believed to be unfeasible for genuinely interacting models. Conversely, here we show that the standard quasiparticle picture of the entanglement evolution, complemented with integrability-based knowledge of the asymptotic state, leads to a complete analytical understanding of the entanglement dynamics in the space-time scaling limit. Our framework requires only knowledge about the steady state, and the velocities of the low-lying excitations around it. Everyone is welcome to attend!
  • Apr. 23 - Apr. 24: Vincenzo Alba from Statistical Physics SISSA, Trieste, is visiting our group
  • Mar. 12: Lluis Hernandez Mula, already master student in our group, joins the AG Läuchli as a new PhD student
    Welcome Lluis!
  • Feb. 26: Defensio (Master) of Lluis Hernandez Mula "Novel numerical techniques for solving Many-Body Localized systems"
    At 10:00 | SR 1, ICT building | Everybody is welcome to join!
  • Feb. 05 - Feb. 07: Stefan Weßel and Stephan Heßelmann from RWTH Aachen are visiting our group
  • Jan. 05: ESQ Postdoc-Fellowship for Dr. Lauri Toikka
    Five young scientists are being funded by Austria’s new Erwin Schrödinger Center for Quantum Science & Technology, and Lauri Toikka from the New Zealand Institute for Advanced is one of them. We are glad to announce that Lauri will start his 2-year PostDoc fellowship within our research group in May 2018!

News from the Department

Further news are available on the German website  

Nach oben scrollen