20 OCT 2021
13:30 - 15:00

After a brief review of the machinery of stochastic inflation, I introduce a model with a sharp transition in the potential and derive the statistics of the stochastic noise. Then I show how to calculate the probability distribution of curvature perturbations from the corresponding adjoint Fokker-Plack equation. Finally, I make some comments on the tail of the distribution and the relation with primordial black holes.

20 OCT 2021
14:00 - 15:00

Abstract: The quality of synchrotron radiation is essential to the users, and its improvement is considered an arena of competition between light sources. RF cavity is one of the components of a synchrotron machine that can affect its quality significantly. When excited by the electron beam, higher-order modes of the RF cavity can cause instabilities in the electron beam itself. Hence, identifying such modes' properties and their impact on the beam quality is critical when developing a synchrotron light source. This talk describes the coaxial wire method as an accurate measurement technique for the longitudinal HOMs of our laboratory prototype RF cavity and compares the results with the previously achieved ones via the R/Q method.


Indico: https://indico.particles.ipm.ir/indico/event/436
https://meet.google.com/rqy-sgfp-jou

19 OCT 2021
17:00 - 18:00

Abstract: For a generic quantum many-body system, the quantum ergodic regime is defined as the limit in which the spectrum of the system resembles that of a random matrix theory (RMT) in the corresponding symmetry class. In this talk I will discuss the time dependence of correlation functions of operators in the SYK model, in the ergodic limit as well as their approach to the ergodic limit which is controlled by non-universal massive modes. An effective field theory (EFT) corresponding to the causal symmetry and its breaking describes the ergodic phase. I will discuss the topological expansion of the resulting Goldstone-mode theory where the leading non-trivial topologies give rise to the universal ramp seen in correlation functions. Furthermore we analytically capture the plateau behaviour by taking into account the contribution of a second saddle point. These results explicitly establish the validity of the EFT description in the SYK-class of models, starting from their microscopic description. I will discuss the tower of massive modes above the Goldstone sector that govern how the ergodic EFT phase is approached and derive the relevant Thouless time scales.
In the second part of the talk, I will discuss the connections between the Eigenstate thermalisation hypothesis (ETH) and the Euclidean wormholes. Motivated by this connections I will discuss our proposal for ETH for charged operators in quantum theories with global symmetries.

( for participating in this event, please contact us: "particles@ipm.ir" )

14 OCT 2021
10:00 - 18:00

Workshop (online)
Oct 14 , 2021 from 10 to 18

13 OCT 2021
16:00 - 17:00

The technological and theoretical advances in the past decades have led to the reemergence of machine learning (ML) applications in physical sciences providing unprecedented opportunities to find efficient and accurate solutions to the most challenging problems in these disciplines. Finding the electronic structures of real-world materials is one of the prime examples of such problems in quantum chemistry and condensed matter physics as they will shape the fundamental understanding of dynamics and evolution of electronic and magnetic properties. In this talk, I will present a brief review of the current state of ML applications in material sciences and also share some of our projects in the field of quantum chemistry. As an example, we will consider a neural network (NN) representation for approximating the full configuration interaction (FCI) wave function. The configuration interaction approach is considered to be a highly accurate representation of the exact wave function, and, in principle, can capture both the static and dynamic correlation effects in many body quantum systems. However, the exponential growth of the Hilbert space dimension with the number of electrons basically diminishes the prospect of using the FCI method for many interesting quantum systems. It will be shown that the NN wave functions are highly compact and accurate representations of the exact electronic structures when tested in a benchmark set of molecular systems.


To join the seminar, please follow this link:

https://www.skyroom.online/ch/schoolofnanoscience/weeklyseminars

and log in as guest.

13 OCT 2021
11:00 - 12:00

Abstract: In the context of gauge/gravity duality, it is known that some information-theoretic quantities in a quantum field theory may have a simple geometric description in a dual gravitational theory and vice versa. The most famous example should be the (entanglement) entropy that is related to the area of a certain extremal surface in a higher dimensional theory of gravity. In this talk, I will briefly review this dictionary and focus on the concept of Entanglement Wedge Cross-Section and its dual descriptions as a measure of correlation in mixed states. In particular, I will argue how this quantity may describe the thermalization process of a conformal field theory after a global quench.


Indico: https://indico.particles.ipm.ir/indico/event/432
https://meet.google.com/zfx-datc-ocm

13 OCT 2021
15:30 - 17:30

I will discuss how the property of "largeness" of a field (introduced by Pop) can be used in the model theory of fields to help solve conjectures and questions about fields whose first order theory is stable or simple. This is a joint with Erik Walsberg.

https://us06web.zoom.us/j/87929792112?pwd=WWNnTkEwOFQwRDdOVXNaK1UzZHBFZz09
Meeting ID: 879 2979 2112
Passcode: 496589