Context: 

With the advent of optical atomic clocks, precision measurements have entered a new era. Fractional frequency accuracies have reached the 18th decimal, and are now providing key insights into faint fundamental phenomena. Yet, the current limitations of traditional, “passive”, optical clocks are now challenging to overcome, and new optical frequency keepers are emerging. Among them, one exciting perspective is to realize superradiant lasers. They are based on cold atoms with a narrow-linewidth optical transition coupled to a high-finesse Fabry-Perot cavity. Superradiance emerges as the constructive quantum interference between the various decay paths from a many-body fully excited state to the ground state. A superradiant laser uses directly the enhanced atomic emission inside the cavity as the ultra-stable signal.

The project:

The next experimental objective is to transport ytterbium atoms to the cavity via an optical conveyor belt. In the cavity, we will perform high-resolution spectroscopy of an ultra-cold ytterbium ensemble coupled to a single mode high finesse Fabry-Perot cavity to estimate the atom-cavity coupling. The next objectives will focus on the first observation of superradiance on the clock transition of ytterbium. Then, we will transport a second atomic ensemble inside the cavity and study the emergence of quantum correlations between the two ensembles.