Ultracold atoms in 1 d optical lattices experiments towards quantum chaos and atom interferometry

Abstract

The present thesis aims at addressing two major problems using the interaction of ultracold atoms with 1 D lattice The initial goal was to set up a cross optical dipole to generate a Bose einstein condensate This would provide a basic platform in order to realize the problems of our interest An existing experimental set up capable of producing laser cooled atoms was used to realize the Bose Einstein Condensation in an optical dipole trap The problems addressed using this system are as follows a Demonstration of non exponential quantum decoherence in a Levy kicked rotor system and b Realization of diffraction of an atom laser in Raman Nath regime A major part of this thesis was to demonstrate experimentally the non exponential decoherence in a Levy kicked rotor system This experiment addresses one of the fundamental problems in quantum mechanics known as decoherence In general quantum systems lose coherence exponentially fast upon interacting with the environment and this puts a limititations on some technological applications using Quantum systems for e g on the Quantum gate operation time and efficiency in Quantum information processing and precision metrology In this work we used an atom optics delta kicked rotor subjected to non stationary Levy noise in the kicking sequence and demonstrated slower than exponential decoherence manifested in the form of sub diffusion in the mean energy growth of the rotor To realize the system experimentally using cold atoms we used a cold cloud of atoms having Maxwell Boltzmann distribution in momentum space and made it to interact with a pulsed 1 D optical lattice to realize the kicking sequence By controlling the kicking sequence we studied the decay of coherence in the system This work is extremely relevant in the context of understanding the dynamics in disordered nonlinear lattices and diffusion in chaotic quantum systems This work will also be helpful in understanding fundamental problems related to quantum mechanics and non linear dynamics of chao newline newline