Events
Condensed Matter Seminar
Spectral gaps and dynamical transitions in random open quantum systems
Prof. Dror Orgad
The Hebrew University of Jerusalem
Mon, 10 Nov 2025, 11:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: The way nonequilibrium systems relax to their steady states is the subject of extensive research. This talk addresses the universal features of such dynamics in open quantum systems. Specifically, I will discuss the relaxation rate of a chaotic quantum system coupled to noise, using a random matrix model where both the Hamiltonian and the system-noise coupling exhibit power-law distance dependence. I will demonstrate the existence of three distinct dynamical phases, characterized by the behavior of the spectral gap of the Liouvillian superoperator that generates the dynamics. One phase is gapped and relaxation is asymptotically exponential. Conversely, the other two phases are gapless and exhibit subexponential relaxation, distinguished by the scaling of the vanishing gap with system size. I will also describe several spectral features emerging in the limits of weak and strong decoherence.
Particles and Fields Seminar
Energy transport across interfaces in CFTs
Dr. Sebastian Waeber
BGU
Mon, 10 Nov 2025, 14:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: Energy transmission across conformal interfaces between 2D CFTs is universal, the transmission coefficients do not depend on the shape and composition of the wave packet. Transmission and reflection coefficients in 2D can be expressed in terms of interface CFT parameters and computed via holographic methods. In higher dimensions the situation becomes much richer and more involved. I will present work in progress on computing energy transmission across interfaces in higher dimensional CFTs and comment on recent results for head-on collisions, explicitly deriving the transmission coefficients in 3D and 4D.
Physics Colloquium
Time reversal symmetry and spin selection in spintronics
Prof. Amnon Aharony
BGU/TAU
Tue, 11 Nov 2025, 16:00
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015
Abstract: Spintronics replaces electronics, by using both the charge and the spin of the electrons. Quantum information is contained in qubits (two-componennt spinors). Here we discuss mobile (flying) electrons, which can carry such quantum information. Tuning this information involves electric and magnetic fields, which vary geometrical and topological phases on the related spinors. Although the spin-orbit interaction (which determines the Aharonov-Casher phase) is a major tool for such tuning, it is often not sufficient, because it conserves time-reversal symmetry. The talk will describe several ways to break this symmetry, and allow spin selection, both for a mesoscopic interferometer and for helical molecules.
Astrophysics and Cosmology Seminar
Probing the Interiors of Massive Stars with Asteroseismology
Ms. Noi Shitrit
TAU
Wed, 12 Nov 2025, 11:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: Massive stars are the progenitors of many astrophysical systems and key to understanding many astrophysical processes, yet important aspects of their structure and evolution are not well understood. Asteroseismology, the study of stellar pulsations, is a unique way to probe the interiors of stars. However, doing so for massive stars is observationally challenging, with the first such study taking 20 years to resolve the six main pulsation modes for a single star. Long-term continuous observations can reduce this time span, but require either space-based campaigns (which currently produce only single-band data, which is not enough for full asteroseismic modeling), or global coordination between ground-based telescopes (which has been difficult to scale to many stars). This is why to date, fewer than 10 massive stars have been fully modeled through asteroseismology. Using a global network of identical robotically-coordinated telescopes, we are tripling this sample within 3 years. This will help move the field of massive-star asteroseismology from single case studies to population analyses. I will present our observational and modeling methods and show some initial results. If time allows, I will also present a complementary method and tool we're developing for constraining massive-star physics - through their supernovae - allowing to probe the latest stages of their evolution.
Quantum optics seminar
Controlling out-of-equilibrium nano-systems to reach the quantum regime
Dr. Salambô Dago
University of Vienna
Wed, 12 Nov 2025, 16:00
Zoom only
Abstract: Link: https://us02web.zoom.us/j/85132785818?pwd=MWO1qfavecdoRvQRK8FaPa75l68jGC.1
Feedback control provides a versatile tool for manipulating nanoscale systems dominated by thermal or quantum fluctuations. We present applications of feedback to reach the quantum regime with nano-objects. We introduce FLIP (Feedback Stabilization on an Inverted Potential), a novel feedback scheme combining Kalman filtering with optical trapping to achieve quantum control [1] and ground-state cooling of levitated nanospheres. This approach allows stable levitation in a double-well configuration while mitigating absorption, opening new routes for optical manipulation at the quantum limit [2].
[1] L. Magrini, P. Rosenzweig, C. Bach, A. Deutschmann-Olek, S. G. Hofer, S. Hong, N. Kiesel, A. Kugi Nature 595, 373 (2021).
[2] S. Dago, J. Rieser, M. Ciampini, V. Mlynar, M. Aspelmeyer, A. Deutschmann-Olek et N. Kiesel Optics Express 32, 45133-45141 (2024)
Biological and soft-matter physics
A Model of Epigenetic Inheritance Accounts for Unexpected Adaptation to Unforeseen Challenges
Prof. Yitzhak Rabin
Dept. of Physics, BIU
Thu, 20 Nov 2025, 12:00
Sacta-Rashi Building for Physics (54), room 207
Abstract: Accumulated evidence of transgenerational inheritance of epigenetic and symbiotic changes raises fundamental questions about the possible types, significance and duration of impacts on the population, as well as whether, and under which conditions, the inheritance of non-genetic changes confers long-term advantage to the population. To address these questions, a population epigenetics model of individuals undergoing stochastic changes and/or induced responses that are transmitted to the offspring is introduced. Potentially adaptive and maladaptive responses are represented, respectively, by environmentally driven changes that reduce and increase the selective pressure. Analytic solutions in a simplified case of populations that are exposed to either periodic or progressively deteriorating environments shows that acquisition and transmission of non-genetic changes that alleviate the selective pressure confer long-term advantage and may facilitate escape from
extinction. Systematic analysis of outcomes as a function of population properties further identifies a non-traditional regime of adaptation mediated by stochastic changes that are rapidly acquired within a lifetime. Contrasting model predictions with experimental findings shows that inheritance of dynamically acquired changes enables rapid adaptation to unforeseen challenges and can account for population dynamics that is either unexpected or beyond the scope of traditional models.
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