Thursday, July 13, 2023
MLIT Room 310
I. V. Amirkhanov, I. Sarkhadov, Z. K. Tukhliev

Numerical results of thermal processes occurring in materials under the action of femtosecond laser pulses

Speaker: I. Sarkhadov

The study of the interaction of femtosecond laser pulses with matter is important due to many fundamental problems (physics of nonequilibrium processes, generation of shock waves, laser acceleration of ions, etc.). Currently, there is an increasing need to create and improve reliable physical models capable of describing various processes in matter. At the same time, computer modeling now occupies one of the main places in the study of such problems.
The paper proposes a modification of the thermal peak model (TPM) based on a system of two coupled hyperbolic heat conduction equations. The action of the laser in the electron gas is taken into account through the source function, which was chosen in the form of a double femtosecond laser pulse. In the hyperbolic TPM, in contrast to the parabolic TPM, there are additional parameters that characterize the relaxation times of the heat flux in the electron gas and the crystal lattice.
A numerical study of the solutions of the parabolic and hyperbolic equations of the thermal peak model for the same physical parameters and a comparative analysis of the results obtained are carried out.

V. Abgaryan

On the convex structure of the set of absolutely separable states and their relation to Wigner positivity

It is quite intriguing, that among mixed states there are such, that are separable under global unitary transformations, which makes it impossible to entangle the corresponding local degrees of freedom with unitary dynamics if the initial state is from the aforementioned class. In this report we are aiming at describing the facial structure of the boundary of absolutely separable (AS) states, including giving the solution to an open problem of finding its extreme points (in the case of most relevant for quantum information theory - 2 x d systems). In the second part of the report, pivoting on the globality of Wigner Positivity (WP) we describe the interrelation of these two sets (WP vs. AS).