Doubling Cavity for Atom Interferometry with Momentum Squeezed States for Gravitational Sensing

Atom interferometers are evolving rapidly and are used in a variety of applications in fundamental physics such as the precise measurements of gravitational constants, curvature and, more recently, waves. The Kasevich group has begun constructing a new atom interferometry experiment based on Strontium with the objective of using spin squeezing to demonstrate quantum-enhanced inertial sensors. The experiment will incorporate a large-momentum-transfer (LMT) Bragg interferometer on the 461nm $^{1}S_0$$\leftrightarrow$$^{1}P_1$ transition in $^{88}$Sr to coherently generate and control well defined atomic momentum state superpositions. A ring resonator with a bow-tie configuration was designed, built and optimized to convert 922nm light from a Ti:Sapph laser to 461nm. The Pound-Drever-Hall technique was implemented to lock the cavity resonance to the laser frequency. Up to 1W of 461nm light was produced with a conversion efficiency of 60%. Noise suppression was achieved by stabilization with acousto-optic modulators. Second harmonic generation was also achieved with a periodically-poled crystal in a single-pass configuration.