My research interests are on theoretical matters related to atoms. These span a wide range of very exciting and challenging research areas. Be it the nature of fundamental interactions or the physics of galaxies or phenomena in condensed matter physics or quantum chaos or precision time keeping, it is of immense value to know atoms to fine detail. It is interesting and amazing to study how atoms respond to external fields. Depending on the nature of the field and how it is applied, one can have a peek at the inner workings of an atom or collection of atoms. Some of the revelations could be far reaching and of fundamental importance. My current research interests are:
In the near future I shall continue to work on research projects related to the above topics. As long term undertaking, I have initiated research work on the following topics:
Results from the studies of discrete symmetry violations in atoms, molecules and solid state systems have important implications to fundamental physics. Currently, there are experiments in several labs to measure the effects of P violation, P and T violation, and CPT nonconservation. To mention a few, our collaborator Dmitry Budker and coworkers are measuring the parity nonconservation effects in atomic Yb and P and T violation in solids. Fortson and coworkers measured EDM, the signature of P and T violation to high precision in atomic Hg. Mike Romalis and his group conducts experiments to detect CP and CPT violations.
The Bose-Einstein condesate (BEC) of the bosonic cold atoms is an interesting state of matter. The importance and impact of which can be far reaching as lasers. The BEC of cold atoms was first observed by Wieman and Cornell, Ketterle, and Hulet. Among whom Cornell, Ketterle and Wieman were awarded the Nobel Prize in 2001 for their work on BEC of alkali atoms. Subsequently BEC of alkali atoms in fine detail. In a recent work, our collaborator Yoshiro Takahashi has observed BEC in atomic Yb. The ultracold fermionic atoms are important to understand BCS state in finer detail. Fermionic alkali atoms were first cooled to degeneracy by Jin. After several experiments, Ketterle first observed BCS pairing without ambiguity
Finding new laser transitions, atomic clock transitions, precision spectroscopy, etc of atoms require accurate atomic structure and properties calculations. Out of all the atoms listed in the periodic table only Hydrogen atom is exactly solvable, which is also one of the few realistic exactly solvable quantum systems. The calculations become complicated and challenging for heavy atoms, which have to be done relativistically. We use a variety of many-body methods, coupled-cluster or related methods are the ones we use. These are considered the best methods. In these endeavours we collaborate with Debashis Mukherjee, one of the leading experts of coupled-cluster method.
Quantum many body systems like nuclei, atoms, molecules, etc. exhibit very complex properties. In these systems it is near impossible to do spectroscopic studies of the highly excited states. A possible way out of this difficult situation is to use statistical methods. Random matrix methods provide a way to study the physics of highly excited states and make predictions. The embedded random matrix ensembles have found wide applications in the studies of quantum many body systems. V. K B. Kota and collaborators have studied this class of random matrix ensembles. In recent times we have used one type of this class in atoms with interesting results.
Chaos in simple quantum systems like anharmonic oscillators, kicked top, kicked rotor, etc. is inferred from the agreement of the statistical measures with that of random matrix ensembles. An interesting system of study is coupled quartic oscillators.