Experimental problems related with ultra cold atoms

Jean Dalibard, Christophe Salomon

Swati Singh

The work described in this thesis is related to various projects that I worked on towards the production of ultra-cold ensembles of ⁸⁵Rb, ⁸⁷Rb and fermionic ⁶Li. In the past few years, ultra-cold atomic gases have evolved into a mature field of research, driving various theoretical and experimental groups towards new possibilities. This thesis starts with an overview of the research direction of the field and the lab in particular, to use ultra-cold fermionic atoms as quantum simulators for several condensed matter problems. It discusses the experimental route to quantum degeneracy in a sample of ultra-cold atoms and techniques to get there. The rest of the thesis primarily discusses the first step to degeneracy- production of ultra-cold ensembles of rubidium and lithium. It starts with the theoretical concepts that enable laser cooling and trapping. The interaction between light and atoms and how it leads to a decrease in temperature of the ensemble is discussed. The limits of different cooling mechanism with relevance of the atoms of interest are described. The starting point for all laser cooling experiments is an atomic source, the details of the requirements and efficiency of different atomic sources is discussed, emphasizing our choice of sources for the two atoms. Other technical details such as the vacuum system and the control system for the experiment are briefly discussed. Preliminary data from our first ensembles of ultra-cold lithium and rubidium is shown. At the end, the planning and progress of the first experiments that we aim to achieve with these ultra-cold atoms namely looking for Feshbach resonances and studying the effect of DC electric fields on them, and studies with ultra-cold lithium atoms in optical lattices, is discussed.

Sanjay Moreshwar Wagh

General Principle of Relativity unequivocally supports the notion of momentum-less energy for bodies (energy-quanta) moving at the {\em same} or {\em constant} speed relative to all the reference systems. In this communication, we point out that whether energy-quantum is a momentum-less body or not is verifiable using ultra-cold atoms trapped in an optical lattice, perhaps with some minor modifications to the existing such experimental setups.

Renato Ejnisman, Paul Rudy, N. P. Bigelow +5 more

Chongming Yang

Frédéric Chevy, Christophe Mora

Recent experiments with ultra-cold atoms have demonstrated the possibility of realizing fermionic superfluids with imbalanced spin populations experimentally. We discuss how these developments have shed new light on a half-century-old open problem in condensed matter physics, and raised new interrogations of their own.