Amlan Datta Email & Phone Number

Ames, Iowa, United States

Ames, Iowa, United States

Ames, Iowa, United States

Graduate Research Assistant in Department of Physics and Astronomy

Ames, Iowa, United States

Ames, Iowa, United States

Kolkata, West Bengal, India

A Master Equation Approach to Spin Noise.investigating and modelling of spin noise using a modified form of the quantum master equation. Spin noise is one of the key evidences of the presence of thermal fluctuations of an ensemble of spins in thermal equilibrium. The usual explanations of spin noise is as follows: if an ensemble contains n no of spins then at thermal equilibrium √n no of spins are in the transverse plane, which eventually gives the signal of spin noise. However experiments shows the no of spins causing the signal of spin noise must be larger than √n. Therefore in order to explain the experiments, a better model of spin noise is needed. So, in the present thesis I will investigate the quantum origin of spin noise using a quantum master equation(QME). The analysis will involve solving the spin dynamics both analytically and numerically and finally quantifying the no. of spins required for the spin noise signal. I will focus on the precise measurements of spin noise in solvents like water, alcohol etc. using the liquid NMR spectroscopy.

Hamburg, Hamburg, Germany

Experimental and Theoretical Investigation of Photofrgamentation Mechanisms of PolycyclicAromatic Hydrocarbons (PAHs) Exposed to XUV Radiation.Ultrashort laser pulses are used as an essesntial tool for triggering and probing the femtosecond dynamcs by interaction with the target molecule. In this work we have analyzed experimental data obtained at free electron laser in Hamburg (FLASH), that produces pulses with XUV photon energy.The first part of the report contains the analysis of the partial covariance maps of three PAHs of our interest: Fluorene, Phenanthrene and Pyrene. This is an investigation of mechanisms behind photofragmentation of these molecules subjected to harsh XUV radiation. The idea for that is to simulate the processes appearing in the interstellar medium (ISM), when the PAHs are excited by spaceous syncrotron radiation sources (such as Crab Nebula, etc.). The results from the time-of-flight – time-of-flight (TOF-TOF) partial covariance maps of these molecules are presented and analyzed to observe their behaviour under XUV excitation.The second part is theoretical modeling of the photochemical dynamics. It is inspired from the experimental results of some ultrafast pump-probe dynamics research going on all over the world including the study depicted in the first part of the report. Simulations are very nice tool in science to analyze the phenomena happening in the labs. So, in addition to pure experiment, simulation methods are implemented to see whether they match with the experimental data. We have focussed on the single photon excitation processes only and we have taken the reference accordingly. Most importantly we are concerned more about the nuclear dynamics which leads to better understanding of fragmentations in pump-probe experiments. Also the result or more specifically the pump-probe fragmentation dynamics yields from the simulations will lead us better understanding of the physics of these processes in pump-probe experiments.

Kolkata, West Bengal, India

Measurement of the surface tension and viscosity of a liquid using the capillary waves as diffraction grating.Apart from the conventional method of measuring surface tension and viscosity of a liquid, we are taking the help of optics to measure those quantities. Capillary waves are generated on the liquid surface and the crests formed are used for diffraction grating. The dispersion relation of capillary waves has been used to determine the surface tension of water. For viscosity we have used the fact of dependence of amplitude of the capillary waves on the root mean square voltage of the signal driving the capillary waves. The surface tension and viscosity of distilled water is verified and how surface tension varies with the addition of any kind of salt, surfactant and alcohol to water is also observed. There is an interesting trend in the variation of surface tension of water with the variation of concentration of salt solution and alcohol-water mixture.

Varanasi, Uttar Pradesh, India

Entanglement and Mutual Information in Many-Body Localized Quantum Systems.In this project we have two models for both interacting and non interacting particles (Many-body localization and Anderson localization respectively). We study entanglement entropies and mutual information for the two models and understand the structure of the many-body localization by analyzing structures of single site entanglement entropy, two site entanglement entropy, mutual information and half-chain entanglement entropy for both time independent and time dependent Schrodinger equation. We find that the entanglement entropies decrease almost monotonically with increase in disorder strength, whereas mutual information is not monotonic. We also see some interesting properties which depend on the periodic boundary condition.

Doctor Of Philosophy - Phd, Condensed Matter And Materials Physics

Bachelor Of Science - Bs, Physics

Doctor Of Philosophy - Phd, Physics