High resolution spectroscopic measurements with ultracold ions in a Paul trap

A precise measurement towards a fundamental physics problem i.e. Atomic Parity Violation (APV) in atomic systems aims at the determination of a parameter, the electroweak mixing Weinberg angle (sin2θW) at low momentum transfer. The precision to which sin2θW can be determined depends on the accuracy of the knowledge of the atomic structure of trapped and laser cooled simple alkaline earth Ba+ ion and its intrinsic sensitivity to the high precision measurements. This research work includes the available information on the atomic system Ba+ and experimental inputs for verification of recent improved calculations for Ba+ wavefunctions. A single ion localized to better than one optical wavelength is a necessary prerequisite for such a precision measurement. A single Ba+ ion experiment has been constructed for this purpose and the frequency stabilization techniques for the employed laser systems have been implemented. The information on the lifetime of the long lived 5d 2D5/2 state in single and multiple ions, level energies and light shifts of order a few Hz of Zeeman sublevels of the 7s 2S1/2 ground state in the presence of the additional laser field in single Ba+ ion forms a crucial step towards determination of APV in a single trapped ion. These precise measurements give an excellent understanding of the complex spectra of Ba+ with a 8-level system including the hyperfine Zeeman levels.
The research experience with trapped and laser cooled Ba+ ions will be employed towards setting up an experiment employing an atom-ion hybrid system. In such an atom-ion hybrid system, the ions will be trapped and laser cooled in a Paul trap and sympathetically cooled by atoms in a magneto-optical trap (MOT). The study of interaction between ions and atoms at ultralow energies will be starting point towards understanding the spin dynamics of ions via the collision processes. Further, the quantum decoherence observed will serve as input data for controlling open quantum systems important for quantum information processing.