SCIENCE DIRECTIONS
Preamble
Our
primary research thrust is in the direction of ultra-cold molecules and
ultra-cold dipolar molecules. We are developing the laboratory to study
problems related to these topics experimentally. This is a very promising and challenging
emerging area in the field of cold dilute gases. The inherent complexity of
molecules makes it rather difficult to adopt the technologies which are well
developed for their atomic counterpart. We therefore have before us the dual
task of studying exciting new physics and inventing the enabling technologies
for it.
Motivations
The cooling and trapping of atoms has provided
fertile ground for exploring a wide range of problems in physics. In the future
these systems are likely to play a pivotal role in our understanding of many
body systems and several other important issues in physics. In order to tap
into these potential problems it is vital to understand the basic interactions
in cold dilute gases. For cold dilute atoms, the vast majority of the physics
explored relies on 2-body spherically symmetric interactions, the so called
s-wave interaction. This is because at very small kinetic energies only the
lowest angular momentum quantum number dominates the interaction. However there
exists no fundamental reason why the physics of interest must limit to isotropic
interactions. The study of anisotropic interactions, in cold dilute gases, is
therefore perceived to be an area with tremendous potential in the future. It
is these anisotropy driven situations that we wish to pursue as the principle
thread in the present experimental program, leading us to our studies with
molecules.
Ultra-Cold Molecules
In the case of diatomic molecules two different
classes of molecules exist; viz. homonuclear and heteronuclear molecules. Homonuclear
molecules are built up from two identical atoms whereas heteronuclear
molecules arise from the bonding of two different atoms. If in addition, the
atoms making up the molecule are chemically distinct, and the bond length is
relatively small, these molecules in addition exhibit a “permanent” electric
dipole moment. Such molecules exhibit long range and anisotropic potentials,
giving interactions between two such molecules a tensor character. This is
therefore a very intriguing system at ultra-cold temperatures, where the
kinetic and potential energy driven mechanisms of such collective systems can
be studied in competition.
The Experimental System
We are at present in the final stage of construction
of a vacuum system where we can do laser cooling on both Rubidium (Rb) and Potassium (39K, 40K). The
basic idea is to first laser cool these alkali atoms. Following the cooling and
trapping of atoms, various techniques for forging bonds between the atoms shall
be attempted. We wish to create both tightly and loosely bound molecules, both homonuclear and heteronuclear.
Strategies for trapping these molecules/manipulating them and detecting them
nondestructively need to be developed. The techniques for accomplishing all
these objectives are largely yet to be invented/developed.
This is true not just for the experiment at RRI but of similar experiments
across the world. Thus major experimental challenges exist in this field making
it a very exciting and potentially rewarding branch of contemporary physics.
Other Research Interests
In addition to the
above directions, we are also actively looking at studying the interactions of
atoms and molecules with external fields. High resolution precision
spectroscopy of atoms and molecules are of considerable interest to us as is
development of microscopy for tackling specific problems of interest. Most
recently we have encountered an interesting phenomenon involving surfaces that
we are looking into. We are also building a variety of optical instruments of our
own design for various applications.