[Landau ITP Seminars] Thursday 17.04.2025 - ITP/CAS Colloquium

[info+seminars at itp.ac.ru]

Уважаемые коллеги!

На онлайн коллоквиум по теоретической физике в четверг 17.04 будут заслушаны 2 доклада:

1) 10:00:00 по московскому времени: Wei Li (Institute of Theoretical Physics, Chinese Academy of Sciences)
Tensor Networks Approach for 2D Correlated Electrons: Implications for High-Tc Superconductivity

Abstract
Two-dimensional correlated electronic systems present a fundamental challenge in condensed matter and quantum physics. Thermal tensor networks have emerged as a powerful tool for finite-temperature studies of many-electron systems. In this talk, I will present our recent advances in thermal tensor network methods, focusing on two recent developments: (1) exponential tensor renormalization group (XTRG), which achieves exponential acceleration through density matrix operator squaring, and (2) the efficient tangent-space tensor renormalization group (tanTRG) that incorporates time-dependent variational principle (TDVP) techniques. Our tensor network methods enable accurate low-temperature simulations of fundamental models like the Hubbard and t-J Hamiltonians, as well as material-specific applications such as the t-t'-J model for cuprates and the t-t-J⊥ model for bilayer nickelate superconductors.

Biography
Dr. Wei Li obtained his Ph.D. in Theoretical Physics from CAS in 2012, followed by postdoctoral research at Ludwig-Maximilians-Universität München (2012–2015). He served as an Associate Professor at Beihang University before joining the Institute of Theoretical Physics (ITP-CAS) as a Research Scientist in 2021. His research focuses on strongly correlated quantum systems, including quantum magnetism and correlated electron phenomena, development of novel tensor-network methods, and applications to cutting-edge problems in many-body physics. He has published over 80 papers in leading journals including Nature, Nature Physics, and PRL. He currently leads a CAS-sponsored Youth Innovation Team focused on foundational research in quantum many-body physics and applications.


2) 11:00:00 по московскому времени: Igor Burmistrov (L.D. Landau Institute of Theoretical Physics, Russian Academy of Sciences)
Dynamics of Phonons in Flexible Two-Dimensional Materials

Abstract
In this talk, I will discuss the microscopic theory for the attenuation of out-of-plane and in-plane phonons in free-standing and stressed flexible two-dimensional crystalline materials. In the free-standing case, it is possible to find exactly the scaling form of the attenuation, determine its small- and large-frequency asymptotes, and to derive the exact expression for the dynamical exponent of flexural phonons in the long-wave limit. In the stressed case, the presence of nonzero tension strongly reduces the relative magnitude of the phonon's attenuation and, consequently, results in parametrical narrowing of the phonon spectral line due to stress-controlled suppression of the retardation effects in the dynamically screened inter phonon interaction. I will discuss how suppression of the phonon attenuation by nonzero tension might be responsible for high quality factors of mechanical nanoresonators based on flexural two-dimensional materials.

Biography
Prof. Igor Burmistrov received two Ph.D.s in Theoretical Physics (in 2004 from Landau Institute and in 2006 from University of Amsterdam) and a Doctor of Physics and Mathematics degree in 2012 from Landau Institute. Since 2006, he is a permanent member of Landau Institute holding now the position of the deputy director. In 2017–2020, he was also a Humboldt fellow at Karlsruhe Institute of Technology. He is APS Outstanding Referee (2021). In 2022, he was elected as Professor of Russian Academy of Sciences. His research area includes electron transport in low dimensional systems, superconductivity, magnetism, elasticity of flexible two-dimensional materials, physics of open and dissipative systems. He has authored more than 110 peer-reviewed papers.



Zoom meeting ID: 890 7187 2369
Пароль: 544845