Date of Completion
Atomic, Molecular and Optical Physics | Physics
In this project I developed a general method of finding the optimal laser excitation for an ensemble of two-level atoms with the primary goal of exciting as many atoms as possible, as quickly as possible, for as long as possible, in order of decreasing priority. Specifically, I simulated the laser excitation of a collection of Rubidium-87 atoms from (n=5, L=0, S=1/2, J=1/2) to (n=5, L=1, S=1/2, J=3/2), by finding numerical solutions to the optical Bloch equations. I optimized the parameters of a linear chirp paired with a Gaussian intensity pulse first neglecting and then including spontaneous emission, and then for a hyperbolic-tangent chirp paired with a squared-hyperbolic-secant intensity pulse including spontaneous emission. Comparing the optimal parameters for the linear chirp both with and without spontaneous emission demonstrated that neglecting spontaneous emission will lead to significant errors, at least when considering Rubidium-87. Comparing the linear chirp to the hyperbolic-tangent chirp (both with spontaneous emission) showed that both chirp shapes lead to excitation of greater than 96% of the population, and that based on my simulations, the linear chirp was slightly better at meeting all three goals of ceiling, speed and endurance. The best of all the excitations that I found using a linear chirp is to use a chirp rate between 0.2 and 0.65 GHz/ns and to use a pulse with a FWHM of 100 ns and a peak intensity of 10 W/cm^2.
Iannitelli, Benjamin, "Numerical Simulations of Chirped Excitation" (2012). Honors Scholar Theses. 274.