Two distinct lasers are shown to permit controlled cooling of a three-level atomic system to a regime particularly useful for group-II atoms. Alkaline-earth-metal atoms are difficult to laser cool to the micro- or nanokelvin regime, but this technique exhibits encouraging potential to circumvent current roadblocks. Introduction of a sparse-matrix technique permits efficient solution of the master equation for the stationary density matrix, including the quantized atomic momentum. This overcomes long-standing inefficiencies of exact solution methods, and it sidesteps inaccuracies of frequently implemented semiclassical approximations. The realistic theoretical limiting temperatures are optimized over the full parameter space of detunings and intensities. A qualitative interpretation based on the phenomenon of electromagnetically induced transparency reveals dynamical effects due to photon-atom dressing interactions that generate non-Lorentzian line shapes. Through coherent engineering of an asymmetric Fano-type profile, the temperature can be lowered down to the recoil limit range.
In this dissertation, I present studies of molecules for uses in quantum science ranging from quantum computing and ultracold collisions to controlling organic-inspired molecular species. Starting with a diatomic molecule, calcium monofluoride, we developed an optical tweezer platform for use in quantum computing and demonstrated rotational coherence times significantly longer than measured dipole-enabled gate times. Using the Tweezer platform, we studied ultracold collisions of exactly two molecules and exerted full quantum control over the internal structure of the molecules. The collisions resulted in a rapid loss from the tweezers, leading us to develop a microwave shield to prevent these lossy collisions. The shielding scheme enhanced the rate of elastic collisions enabling the demonstration of forced evaporative cooling. To explore the possible use of larger molecules for quantum science, we studied the rotational structure of an asymmetric top and aromatic molecule, calcium monophenoxide, with the intent of identifying a path toward laser cooling and trapping. We cycled several photons, but theory predicted many more. After eliminating several decay paths, the key loss remained unknown. Applying the same methods to CaNH
2, a smaller asymmetric top molecule with similar spatial symmetry, we performed laser cooling. Using CaNH
2, we demonstrated photon cycling, and then observed Sisyphus cooling and heating features for the first time using an asymmetric top molecule. This work lays the foundation for future laser-cooling of organic-inspired molecules in an optical tweezer array for applications ranging from quantum computing to quantum chemistry, and precision measurement.
A quantum mechanical Monte Carlo simulation is carried out for one-dimensional laser cooling of Chromium atoms. Chromium atom beam collimation via transverse laser cooling is essential for the fabrication of periodic nanometer scale structures by laser-focused atomic deposition. Such structures can be used as precision pitch standards for nanometer scale measurement and engineering. We explore the roles played by several factors, such as laser intensity and detuning, in the cooling process. Calculation results show different dependencies for cooling rate and ultimate temperature to be reached with given sets of parameters. Also, for atoms with different initial velocities in the transverse direction, the conditions under which optimal collimation effect is achieved can differ. Consequently, the current experimental setup, which utilizes LIF spots from marginal beams to monitor the laser collimation, can produce cooling effects which are not optimal for the end product.