School of Mechanical Engineering Seminar
Wednesday April 19.4.2023 at 14:00

Wolfson Building of Mechanical Engineering, Room 206

"The geometry of decision-making in collectives and individuals"

Prof. Nir Gov

Department of Chemical and Biological Physics

Weizmann Institute of Science

Rehovot, Israel

Choosing among spatially distributed options is a central challenge for animals, from deciding among alternative potential food sources or refuges to choosing with whom to associate. We present a spin-based model that describes the decision-making process while the animal is moving through space and assessing the different options. Using an integrated theoretical and experimental approach (employing immersive virtual reality), we test the predicted interplay between movement and vectorial integration during decision-making regarding two, or more, options in space.  The theoretical model reveals the occurrence of spontaneous and abrupt “critical” transitions, whereby organisms spontaneously switch from averaging vectorial information to suddenly excluding one among, the remaining options. Experiments with fruit flies, desert locusts, and larval zebrafish reveal that they exhibit these same bifurcations, demonstrating that across taxa there exist fundamental geometric principles that determine how, and why, animals move the way they do.

Short bio:

Phd in theoretical physics at the Technion (low-temperature quantum mechanics) 1998

Postdoc at the U of Illinois Urbana-Champaign, QM

Postdoc in Weizmann, Bio-phys.

PI in weizmann since 2004

My research team and I have been developing theoretical models for various phenomena in biology that involve many interacting units, from the collective migration of cells within a body to collective motion of animals within a group. In addition we study the dynamics of cell shapes, cell migration and general non-equilibrium physics.

Join Zoom Meeting

https://tau-ac-il.zoom.us/j/86497933118

Electrical Engineering Colloquium 

Speaker: Prof. Avishay Eyal

Title: Fiber-optic Distributed and Quasi-Distributed Acoustic Sensing (DAS and Q-DAS)

Abstract 

An optical fiber can be described as a glass pipeline which can guide light over great distances with very little loss. In addition to being the central communication channel of the information era, it has another very interesting application. This application is called distributed sensing. By launching into the fiber specially designed pulse sequences of light and analyzing their reflections from different positions along the fiber, it is possible to measure various physical parameters such as temperature, strain and acoustic signals at these positions. During recent years the use of fiber-optic Distributed Acoustic Sensing (DAS) or Quasi Distributed Acoustic Sensing (Q-DAS) systems has become ubiquitous for a variety of applications. Distributed optical fiber sensors are particularly attractive for marine applications. Facilitating long haul sensing or communications systems in the underwater arena is challenging not only due to the need for underwater compatible sensors but also since conventional wireless communication techniques cannot be used to transmit the measured signals. Distributed fiber-optic sensors perform both tasks with the same medium. In the colloquium I will describe techniques that we have developed in our lab for increasing the bandwidth and sensitivity of DAS and Q-DAS systems and will present results of underwater sensing and underwater acoustic communications.

Light refreshments will be served before the lecture

This colloquium is not counted toward seminar credit.

ההרצאה לא מזכה בקרדיט שמיעת סמינרים.

LMI Seminar:

"Ab initio approaches to correlated light-matter interactions“

Prof. Prineha Narang

University of California, Los Angeles

Tuesday  April  4^th,  2022

13:00-14:00

Light refreshments and drinks will be served at 12:30

Auditorium 011, Engineering Classroom Building,  Faculty of Engineering, Tel-Aviv University

Abstract: In this talk, I will present a pedagogical introduction of theoretical and computational approaches to describe excited-states in quantum matter, and predicting emergent states created by external drives. Understanding the role of such light-matter interactions in the regime of correlated electronic systems is of paramount importance to fields of study across condensed matter physics and ultrafast dynamics1. The simultaneous contribution of processes that occur on many time and length-scales have remained elusive for state-of-the-art calculations and model Hamiltonian approaches alike, necessitating the development of new methods in computational physics. I will discuss our latest results at the intersection of ab initio cavity quantum-electrodynamics and electronic structure methods to treat electrons, photons and phonons on the same quantized footing, accessing new observables in strong light-matter coupling. Current approximations in the field almost exclusively focus on electronic excitations, neglecting electron-photon effects, for example, thereby limiting the applicability of conventional methods in the study of polaritonic systems, which requires understanding the coupled dynamics of electronic spins, nuclei, phonons and photons. With our approach we can access correlated electron-photon and photon-phonon dynamics2–7, essential to our latest work on driving quantum systems far out-of-equilibrium to control the coupled electronic and vibrational degrees-of-freedom 8–20. In the second part of my talk, I will demonstrate how the same approach can be generalized in the context of control of molecular quantum matter and quantum transduction. As a first example, I will discuss a cavity-mediated approach to break the inversion symmetry allowing for highly tunable even-order harmonic generation (e.g. second- and fourth-harmonic generation) naturally forbidden in such systems. This relies on a quantized treatment of the coupled light-matter system, similar to the driven case, where the molecular matter is confined within an electromagnetic environment and the incident (pump) field is treated as a quantized field in a coherent state. When the light-molecule system is strongly coupled, it leads to two important features: (i) a controllable strong-coupling-induced symmetry breaking, and (ii) a tunable and highly efficient nonlinear conversion efficiency of the harmonic generation processes 21–23. Both of these have implications for molecular quantum architectures. Being able to control molecules at a quantum level gives us access to degrees of freedom such as the vibrational or rotational degrees to the internal state structure. Finally, I will give an outlook on connecting ideas in cavity control of molecules with quantum information science.