Laser System for the MAGIS-100 Long Baseline, Strontium Atom Interferometer

To this day, dark matter continues to evade detection by our most advanced sensors. Most experiments have focused their search on WIMPs, but astrophysical observations are also consistent with the existence of ultra-light dark matter particles. MAGIS-100 is 100-meter atom interferometer currently being built at Fermilab which will search for oscillations in fundamental constants and time-dependent, equivalence-principle-violating accelerations of test masses: key signatures of several ultra-light dark matter candidates. This presentation will feature our progress on the MAGIS-100 project with a focus on the laser systems and laser manipulation techniques used to generate meter-separated quantum atomic superpositions in the interferometer. We will include details on two laser operation modes, respectively involving coherent combination of two 698 nm lasers for exciting Sr clock transitions (searches for oscillating fundamental constants) and two independent 679 nm lasers for Bragg transitions in two Sr isotopes (searches for oscillating accelerations). In addition to dark matter searches, the interferometer can adapt toward searches for new fundamental forces outside the Standard Model, tests on the coherence limits of spatially separated wave packets. It will also serve as a prototype gravitational wave detector in frequency band between the peak sensitivities of LIGO and LISA.