Events
Physics Colloquium
Research project presentations
Undergraduate Students
BGU
Tue, 25 Mar 2025, 12:00
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015
Abstract: מתן בנימין
Coupling of two-level tunneling structural defects to quantum devices
@Moshe Schechter
יונתן לירז
Linear and nonlinear pattern formation mechanisms near the Hopf-Wave-Turing instability
@Arik Yochelis
רועי מובשוביץ
Growth of La3Ni2O7 thin films
@Muntaser Naamneh
אריאל מצליח
Angular magnetoresistance in infinite layer nickelates
@Muntaser Naamneh
דניאל פולמן
Levitating nano-particles
@Ron Folman
*** There will be refreshments as usual.
Astrophysics and Cosmology Seminar
Afterglow TeV Emission and Prompt Polarization in Gamma-Ray Bursts
Ms. Hevzibha Isravel
BGU
Wed, 26 Mar 2025, 11:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: My talk will delve into the physical mechanisms that power Gamma-Ray Bursts (GRBs), some of the most luminous transient events in the universe. Originating from vast cosmological distances, these bursts appear randomly across the sky, releasing intense pulses of gamma rays that span milliseconds to hundreds of seconds. GRBs are characterized by two distinct emission phases: the prompt phase and the afterglow. The prompt phase features a brief, yet incredibly energetic, burst of gamma rays in the keV–MeV range, lasting from milliseconds to minutes. This is followed by a prolonged afterglow, detectable across a broad spectrum of wavelengths, including X-ray, optical, radio, GeV, and potentially TeV energies. My primary focus will be on modeling the afterglow emission and exploring polarization signatures during the prompt phase. Specifically, I aim to address two key open questions in GRB studies: First, what mechanisms drive the very-high-energy (VHE) radiation observed in the afterglow, particularly in the TeV range? Second, how can we explain the observed 90-degree swings in polarization angle during the prompt phase, and what do these swings reveal about the magnetic field structure within relativistic jets?.
Quantum optics seminar
Building blocks for nanoscale magnetic resonance imaging
Dr. Amit Finkler
Weizmann Institue of Science
Wed, 26 Mar 2025, 16:00
Zoom Only
Abstract: Zoom link: https://us02web.zoom.us/j/87959346785?pwd=NGhnbzgTQCNRNxZNn2If5PUMmuuaKn.1
Abstract:
Telling apart two spins in a single molecule is a daunting task, and yet this is precisely the goal of
nanoscale magnetic resonance imaging (nanoMRI), with ultimate aim of structure, function and
dynamics. In this talk I will first outline the potential benefits of this capability, from fundamental
physics to drug discovery. Then, I will describe the overarching scientific dogma of my research group,
making use of a quantum emitter in the form of the nitrogen-vacancy center in diamond as its central
sensor. Finally, I will describe our work on the building blocks necessary to achieve our nanoMRI
aim. These span magnetic tomography of electron spins with sub-angstrom precision, Bayesian
inference for a boost in acquisition time and strong driving of nuclear spins going beyond the rotating
frame approximation.
Biological and soft-matter physics
What happens to a well-folded (fluorescent) protein within a nuclear bio-condensate
Prof. Eitan Lerner
Department of Biological Chemistry, Hebrew University
Thu, 27 Mar 2025, 12:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: Fluorescent proteins (FPs) are commonly used as fluorescent reporters of the proteins coded by the gene to which the FP sequences are fused. This tool has been used to study many proteins in the cell, including proteins that appear in cellular membrane-less sub-compartments referred to as bio-condensates, some of which are formed via liquid-liquid phase separation (LLPS).
LLPS-formed bio-condensates are amongst the highest-density subcompartments in the cell, to the level in which non-specific protein-protein interactions between disordered protein regions are maximized, and proximities between proteins may lead to effects of macromolecular crowding. In this case, would its fluorescence characteristics change if an FP is genetically fused to one of the protein components of an LLPS-based bio-condensate?
In this talk, I will present my work on such effects on monomeric red fluorescent proteins genetically fused to heterochromatin protein 1 (HP1), which form the basis of heterochromatin bio-condensates. Specifically, I will show that at high local molecular densities, above a given threshold, the fluorescence lifetime of the mCherry chromophore decreases, which can be used to measure the local densities at different regions of a bio-condensate. I will show the mechanism of this effect, and the ability to influence the inner chromophore spectroscopic properties by sensing the outer crowdedness. Then, I will show the use of this effect in identifying the liquid phase characteristic of HP1 bio-condensates or deviations from it, in the context of embryonic stem cell differentiation.
Condensed Matter Seminar
Tweaking the Construction Code: Local Rule Changes and an Emergent Metal-Insulator Transition in Quantum Graphs
Prof. Richard Berkovits
BIU
Mon, 31 Mar 2025, 11:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: The Anderson localization transition in quantum graphs has garnered significant recent attention due to its relevance to many-body localization studies. Typically, graphs are constructed using top-down methods. Here, we explore a bottom-up approach, employing a simple local rewriting rule to construct the graph. Through the use of ratio statistics for the energy spectrum and Kullback-Leibler divergence correlations for the eigenstates, numerical analysis demonstrates that slight adjustments to the rewriting rule can induce a transition from a localized to an extended quantum phase. This extended state exhibits non-ergodic behavior, akin to the non-ergodic extended phase observed in the Porter-Rosenzweig model and suggested for many-body localization. Thus, by adapting straightforward local rewriting rules, it becomes feasible to assemble complex graphs from which desired global quantum phases emerge. This approach holds promise for numerical investigations and could be implemented in building optical realizations of complex networks using optical fibers and beam splitters.
Physics Colloquium
Deep Learning: Some Perspectives from Physics
Zohar Ringel
Hebrew University
Tue, 01 Apr 2025, 12:00
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015
Abstract: Though no match to practical breakthroughs, our theoretical grasp of deep learning has steadily widened during the last decade. This talk will review the past misconceptions and recent new conceptions that have formed, taking a physics standpoint. In particular, I will describe some concrete links to entropy, order by disorder, field theory, and renormalization. I will also discuss the paradoxical nature of trying to understand models meant to solve problems we cannot solve analytically, and ways around this.
*** Refreshments at 12:00, talk at 12:15.
Condensed Matter Seminar
Shedding single-photon light on many-body physics
Mr. Amir Burshtein
TAU
Mon, 07 Apr 2025, 11:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: Photon decay is a notoriously inefficient process. The culprit is the fine structure constant \alpha – while photon splitting into other photons at lower frequencies may be mediated by interaction with matter, the small value of \alpha (~1/137) famously sets this interaction in the perturbative regime. A qualitatively different picture can emerge in superconducting circuits: carefully designed waveguides, implemented by arrays of Josephson junctions, provide an order unity \alpha environment for the photons. Coupling the waveguide to artificial atoms (qubits) then leads to the simulation of strong light-matter interaction, allowing for the decay of a single photon with order unity probability, demonstrated in recent experiments. I will show how this exotic effect can be leveraged to illuminate surprising aspects of fundamental quantum many-body phenomena, observed in experiments from the Manucharyan (EPFL) and Kuzmin (UW-Madison) groups. I will explain how the scattering rates of the photons, natural observables in such experiments, can capture dynamical signatures of quantum tunneling events, reveal the existence of inelastic collisions in integrable systems, and explore the onset and the breakdown of Fermi’s golden rule. I will further show that the scattering of a single photon off an artificial atom can serve as a highly sensitive probe of a fragile quantum phase transition. These works set the stage for utilizing the strong light-matter interaction to study nonequilibrium setups and harnessing the efficient photon splitting for quantum information processing applications.
This talk is mostly based on the following papers (theory and experiment, respectively):
- AB and M. Goldstein, "Inelastic decay from Integrability", PRX Quantum 5 020323 (2024)
- R. Kuzmin, N. Mehta, N. Grabon, R. A. Mencia, AB, M. Goldstein, and V. E. Manucharyan, "Observation of the Schmid-Bulgadaev dissipative quantum phase transition", Nature Physics s41567-024-02695-7 (2024)
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