Alpern Hen

Primary Category:

Graduate Students

Discipline:

Condensed Matter Physics

Office:

Levin 112

Phone:

02 6586 786

E-Mail:

Upcoming Events

Today

Physics Colloquium : "Opto-mechanics in standard platforms: single mode fibers and silicon-on-insulator."
- Start time: 12:00pm
- End date: Monday, December 30th
- End time: 01:30pm
- Lecturer: Avi Zadok, Bar IlanAbstract:The interactions between optical and mechanical waves are often studied in specialty platforms, which enable extensive optimization and support stronger effects. In this seminar, I address the prospects of opto-mechanics in two of the most common, "boring" photonics platforms: the standard fibers and silicon-on-insulator waveguide circuits. While these platforms are not built for opto-mechanics, and leave only limited room for design optimization, they nevertheless support a broad range of interactions between light and ultrasound. Opto-mechanical effects in standard fibers enable the sensing of media outside the boundaries of the cladding, where guided light does not reach. Other effects include non-reciprocal switching of light between the principal axes of polarization maintaining fibers, and a new class of fiber laser. Recent results in few-mode optical fibers will be presented as well. Acoustic waves may be launched along silicon-photonic integrated circuits through thermo-elastic excitation in metallic grating elements. The acoustic waves implement long delay lines, narrowband microwave-photonic filters, thin layers analysis, and microwave-frequency oscillators.
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Tomorrow

Weekly Seminar Quantum Center:"New Avenues for Quantum Information Processing with Light-Matter Interactions"
- Start time: 11:45am
- End date: Tuesday, December 31st
- End time: 01:15pm
- Lecturer: Aviv Karnieli, Stanford UniversityAbstract:Light-matter interaction (LMI) underpins numerous quantum technologies, yet persistentchallenges—such as decoherence, scalability, and speed—limit the advancement ofquantum information processing (QIP) in this promising platform. These limitationsmotivate the search for alternative quantum hardware leveraging LMI to overcomethese barriers and unveil new opportunities for QIP.In this seminar, I will demonstrate how combining diverse concepts, components, andbuilding blocks in quantum optics leads to such novel approaches for QIP. First, I willintroduce free electrons as a new and promising resource in quantum optics, enablingultrafast operation, strong coupling, and single-photon nonlinearities in cavity quantumelectrodynamics (QED). Next, I will show how the integration of concepts from nonlinearoptics into waveguide QED unlocks novel schemes for many-body entanglementgeneration and enables access to exotic physics in atomic arrays. Finally, I will presenta scalable architecture for processing high-dimensional photonic entanglement, inspiredby the variational principle in physics and realized through self-configuring photonicnetworks.Karnieli*, Tsesses*, et al PRX Quantum 5, 010339 (2024)Karnieli and Fan, Science Advances 9, eadh2425 (2023)Karnieli*, Roques-Carmes*, et al, ACS Photonics 11, 3401 (2024)Karnieli et al, accepted to Physical Review Research (2024)Roques-Carmes*, Karnieli* et al, arXiv:2407.16849 (2024)Karnieli*, Roques-Carmes*, et al (submitted to CLE0 2025)
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Astrolunch: Jonathan Katz
- Start time: 12:30pm
- End date: Tuesday, December 31st
- End time: 01:30pm
- Speaker: Jonathan Katz (Dept. of Physics, Washington U. in St. Louis, MO, USA)Title: Star and planet formation and cosmic ray viscosityAbstract:The fraction of planetary mass objects in the Trapezium cluster that are in wide binaries is much greater than implied by extrapolation to lower masses of the fraction of stars that are in wide binaries. In a uniform medium with uniform vorticity the collapse criterion is independent of the size and mass of the collapsing region, which would imply a wide binary fraction independent of mass, in contradiction to observation. Angular momentum, rather than thermal energy (the Jeans criterion), may be the chief obstacle to star formation. The excess of Jupiter Mass Binary Objects in the Trapezium cluster may be attributed to cosmic ray viscosity that transports angular momentum to surrounding material. Viscosity is more effective in smaller and less massive collapsing regions, preferentially producing planetary mass wide binaries. Energetic particles trapped on magnetic field lines in a corona contribute to viscosity, dissipation and angular momentum flow in accretion discs.Zoom link:https://huji.zoom.us/j/81989505874?pwd=vIU5zHP0HRxEmu7Awp8Lq4xIao7LCL.1Meeting ID: 819 8950 5874Passcode: 095544 Contact: Tsvi Piran
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Wednesday, January 1st

Nonlinear Physics seminar: "Electrolytes in bulk and at interfaces: a short review and recent developments"
- Start time: 12:00pm
- End date: Wednesday, January 1st
- End time: 01:30pm
- Lecturer: David Andelman, School of Physics, Tel Aviv University, Israel Abstract:The Poisson-Boltzmann theory stems from the pioneering works of Debye and Onsager and isconsidered even today as the benchmark of ionic solutions and electrified interfaces. It hasbeen instrumental during the last century in predicting charge distributions and interactionsbetween charged surfaces, membranes, electrodes, macromolecules, and colloids. Theelectrostatic model of charged fluids, on which the Poisson-Boltzmann description rests and itsstatistical mechanical consequences have been scrutinized in great detail. Much less, however,is understood about its probable shortcomings when dealing with various aspects of realphysical, chemical, and biological systems. After reviewing the Poisson-Boltzmann theory, I willdiscuss several recent extensions and modifications as applied to ions and macromolecules insolutions. These novel ideas include the effect of dipolar solvent molecules, finite size of ions,ionic specificity, surface tension, charge regulation of ionizable groups and conductivity ofconcentrated ionic solutions.
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Special Seminar Quantum Center:"Quantum measurement through parametric amplification"
- Start time: 02:30pm
- End date: Wednesday, January 1st
- End time: 04:00pm
- Lecturer: Prof. Maria Chekhova, Max-Planck Institute for the Science of Light Erlangen, GermanyAbstract:Quantum states of light are central to photonic quantum technologies, which makes their measurement very important. But quantum states are extremely fragile. Fortunately, a nonlinear-optical device known as the optical parametric amplifier comes to rescue when measurement over a fragile quantum state is needed. It protects the measurement against optical losses and imperfect detection, enables addressing several modes simultaneously, and can substitute homodyne detection with direct detection.
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