讲座题目：On the influence of many-body interactions on the light absorption lineshapes
主讲人：Sizhuk Andrii
主持人：康斯坦丁研究员
报告时间：2019.3.27上午10：00
报告地点：理科大楼A814室
报告摘要：
The theoretical investigation of absorption properties (optical spectrums) of model systems, coupled with quantized electromagnetic field near resonance is discussed.
The model Hamiltonians for the systems with and without a cavity (with and without mirrors) were analyzed. Based on the Schrödinger equation, corresponding microscopic evolution equations for N-particle state function are constructed. Using the microscopic N-particle evolutional equations, the system of macroscopic kinetic equations for the density of probability was derived. The equations describe the time evolution of intrinsic atomic or molecular states in electromagnetic field near the resonant transition, taking into account many-body interaction. The built here theories are applied for the derivation of the kinetics of intrinsic sodium vapor states in a weak and a relatively strong pumping fields. The dependence of absorption coefficient on microscopic parameters, describing interatomic interaction and coupling between the atoms and field, is found.
The absorption line shape for the system of strongly pumped interacting two-level atoms is discussed. Using the analytical expressions for the macroscopic absorption coefficient, derived in kinetic limit for the system interacting with a coherent pump and a weak counter-propagating probe fields tuned near D2 line, the absorption profiles of the probe were obtained for the range of temperatures of sodium vapor from 600K to about 800K. Contribution from different effects is analyzed using the additivity of the corresponding absorption/reemission rates. It was shown, that for the quantum field induced long-range interaction (prevailing over short-range collisions) the broadening, narrowing, and shifts of an absorption line shape can be explained in the terms of interaction integral ("interaction Rabi frequency") coupling the collective atomic polarization and population inversion. The built dependence of absorption coefficient on probe detuning and density of atoms allowed to interpret the experimentally observed gain threshold by means of the interaction integral and predict the qualitatively new behavior of pumped sodium vapor.
The quantum optical theory of absorption/reemission properties of the system of interacting atoms is discussed for the calculation method of the absorption coefficient. The calculation method is developed taking into account the quantization of field, thermal atomic motion, the Doppler effect, and the model interaction between atoms. It was shown that the formulation of the absorption coefficient in the quantum optical context is based on the commutation relation between the operators of electric field and intensity. The revealed non-linear dependence of absorption coefficient on atomic density, even in the case of negligible binary interaction, can be referred to a certain kind of quantum optics collective effect.
报告人简介：
Education
During three years (from 2002 to 2005 y.)Physics Department, Theoretical Physics Department, Taras Shevchenko National University of Kyiv.
Ph.D in physics was obtained by me at Taras Shevchenko National University of Kyiv, Ukraine, in October 2006.
During five years (1995-2000 y.) ,Lesya Ukrainka Volhynian State University
Employment: Research
From 2013 to 2016 doctorate, PhD
RadioPhysics Faculty, Taras Shevchenko Kyiv National University
From 2006 to 2012Research Assistant, PhD student
Dept of Physics 4242 TAMU 408 ENGR PHYSICS BLD, COLLEGE STATION TX
From 2002 to 2005post-graduate student, Research Assistant
Physical Faculty, Taras Shevchenko Kyiv National University
From 10/2001 to 9/2002Lecturer
Gymnasia
From 10/2000 to 11/2001Engineer
Lesya Ukrainka Volhynian State University