<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /></head><body style='font-size: 10pt; font-family: Verdana,Geneva,sans-serif'>
<p><span style="font-size: 13px; font-family: monospace; background-color: #ffffff;">Уважаемые коллеги!</span><br style="font-size: 13px; font-family: monospace; background-color: #ffffff;" /><br style="font-size: 13px; font-family: monospace; background-color: #ffffff;" /><span style="font-size: 13px; font-family: monospace; background-color: #ffffff;">На онлайн коллоквиум по теоретической физике в четверг 27.11 будут заслушаны 2 доклада:</span></p>
<div><strong>1) Ordered and Tunable Majorana-Zero-Mode Lattice in Iron-Based Superconductors</strong></div>
<div> </div>
<div><span>в 10:00</span></div>
<div><span> </span></div>
<div><strong>Hong-Jun Gao (Institute of Physics, Chinese Academy of Sciences)</strong></div>
<div><span> </span></div>
<div><span>Majorana zero-modes (MZMs) are spatially-localized zero-energy fractional quasiparticles with non-Abelian braiding statistics. They are believed to hold great promise for topological quantum computation. By using low-temperature and strong-magnetic-field scanning tunneling microscopy/spectroscopy, a breakthrough of Majorana zero mode has been firstly achieved in a single material platform of high-Tc iron-based superconductor, FeTe0.55Se0.45. The mechanism of two distinct classes of vortices presented in this system was revealed, which directly tied with the presence or absence of zero-bias peak. We further found the Majorana conductance plateau in vortices. Both the extrinsic instrumental convoluted broadening and the intrinsic quasiparticle poisoning can reduce the conductance plateau value, and when extrinsic instrumental broadening is removed by deconvolution, the plateau nearly reaches a 2e2/h quantized value. Moreover, we confirmed the existence of MZMs in the vortex cores of CaK-Fe4As4 and LiFeAs. Based on these works mentioned above, most recently, we have successfully achieved the large-scale, highly-ordered and tunable MZM lattice in strained LiFeAs. Notably, more than 90% of the vortices are topological and possess the characteristics of isolated MZMs at the vortex center, forming ordered MZM lattice with the density and the geometry tunable by external magnetic field. With decreasing the spacing of neighboring vortices, the MZMs start to couple with each other. This kind of materials combine the advantages of a simple material, high- Tc, large ratio of Δ/EF and etc. Our results show a great potential of MZMs in the application of topological quantum computation in the future.</span></div>
<div><span> </span></div>
<div><span><strong>Biography</strong> </span></div>
<div><span>Prof. Hong-Jun Gao obtained his Ph.D. from Peking University in 1994. He is now a Group Leader in Institute of Physics, an Academician of the CAS, and an Academician of the Developing-country Academy of Sciences (TWAS). From 1997 to 2000, he worked at the Oak Ridge National Laboratory (ORNL) as a Guest Scientist. He was the Scientific Secretary of the International Union of Vacuum Science, Technology, and Applications (IUVSTA) in the triennium 2004-2007, and the Chairman of the NSTD, IUVSTA (2010-2013). He served as an Associate Editor for Appl. Phys. Lett. From 2010 to 2018, and are editorial board members for several international journals. He was the Vice-President of the U-CAS and Chair of the U-CAS Advisory Committee of Sciences from 2014 to 2015. In the past years he visited several universities in the US as a Visiting Professor or Scientific Consultant.</span></div>
<div><span> </span></div>
<div><span>His research interests focus on construction and physical properties of quantum nanostructures and scanning tunneling microscopy/spectroscopy (STM/STS). He has 8 international books/chapters, more than 500 journal publications including Science, Nature, Nature series, Phys. Rev. Lett., J. of Amer. Chem. Soc., Adv. Mater., and more than 120 invited talks. The total citation is more than 35000 and the H-index=95. His research works have been highlighted by the American Physical Society–physics, Physical Review Focus, Science News, Nature Materials, and Nature Nanotechnology, etc.</span></div>
<div><span> </span></div>
<div><span>He was awarded several international Awards, including the "Humboldt Research Award" in 2010, the "OCPA AAA (Robert Prize)" in 2008 (OCPA: Overseas Chinese Physics Association; AAA: Achievement in Asia Award), and the "TWAS Prize in Physics 2009" (TWAS: Developing-country (Third World) Academy of Sciences). He also got a few top-level awards in China, for example, "Tan Kah Kee Science Awards on Mathematics and Physics 2018", "Science and Technology Awards of the Ho Leung Ho Lee 2012", and "Outstanding Science and Technology Achievement Prize of the Chinese Academy of Sciences 2013".</span></div>
<div> </div>
<div><span> </span></div>
<div><strong>2) <span style="font-size: 10pt;">Balancing an Inverted Pendulum Under Random Force: Statistics of the Never-Falling Trajectory</span></strong>
<div><span>в 11:00</span></div>
</div>
<div> </div>
<div><strong>Mikhail A. Skvortsov (L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences)</strong></div>
<div><span> </span></div>
<div><span>Various fields of physics involve a class of problems related to minimization of a functional of an angular variable, which depends on a single coordinate, in the presence of a random force. The corresponding second-order differential equation of motion is unstable, making its solution a non-trivial numerical task. A paradigmatic model for this class of phenomena is finding the never-falling trajectory (NFT) of an inverted pendulum subjected to a time-dependent horizontal force (the Whitney problem).</span></div>
<div><span> </span></div>
<div><span>We have shown that the Whitney problem, considered over the entire time axis, has a unique solution, and for the first time, we have raised the question of describing its statistical properties when averaged over an ensemble of random forces. For the white-noise random force, we construct a complete field-theoretical description of the statistics of the NFT, based in the the Parisi-Sourlas supersymmetric representation. The joint probability distribution function of the angle and its velocity is expressed via the solution of an auxiliary Fokker-Planck problem and found analytically in the limits of weak and strong noise. We also determine the Lyapunov exponent, describing the divergence of nearby solutions around the NFT.</span></div>
<div><span> </span></div>
<div><strong>Biography</strong></div>
<div><span>Mikhail A. Skvortsov graduated from the Moscow Institute of Physics and Technology in 1995 and got his PhD in 1998. Since then, he has been continuously employed at the Landau Institute for Theoretical Physics. From 2014 to 2021, he served as an Associate Professor at the Skolkovo Institute of Science and Technology. M. A. Skvortsov is a recognized specialist in the physics of disordered and superconducting systems. His key scientific contributions include explaining the giant fluctuation Nernst effect in superconductors, investigating ergodicity and localization on random regular graphs, developing the Keldysh action approach for disordered superconductors, describing the inhomogeneous state in dirty superconductors, constructing the theory of dynamical localization in quantum dots under periodic driving, characterizing the statistics of the never-falling trajectory in the random Whitney problem.</span></div>
<p><strong style="color: #0f1115; font-size: 16px; font-family: quote-cjk-patch, Inter, system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif; font-weight: 600; background-color: #ffffff;"><span>Zoom: 829 6586 0457, Passcode: 911242</span></strong></p>
</body></html>