Generation of high-purity, low-temperature samples of $^{39}$K for applications in metrology

摘要

We present an all optical technique to prepare a sample of $^{39}$K in amagnetically-insensitive state with 95\% purity while maintaining a temperatureof 6 $\mu$K. This versatile preparation scheme is particularly well suited toperforming matter-wave interferometry with species exhibiting closely-separatedhyperfine levels, such as the isotopes of lithium and potassium, and opens newpossibilities for metrology with these atoms. We demonstrate the feasibility ofsuch measurements by realizing an atomic gravimeter and a Ramsey-typespectrometer, both of which exhibit a state-of-the-art sensitivity for coldpotassium.