Stabilizing dual laser with a tunable high-finesse transfer cavity for single-atom Rydberg excitation

We demonstrate a method to simultaneously suppress the linewidths and stabilize the long-term frequency drifts of both 780-nm and 960-nm lasers to the 10-kHz level. We first use an iodine frequency stabilization laser as a frequency reference to stabilize the length of a tunable high-finesse transfer cavity (THFTC). Then two slave lasers of 780 nm and 960 nm are locked to this THFTC. In this way, the linewidths of slave lasers are suppressed to the order of 10 kHz, which are measured by delayed self-heterodyne measurements. Meanwhile, the long-term frequency drifts are stabilized to be less than 22 kHz for 10 h. With the locked lasers, we realize the coherent Rydberg excitation of a single Rb87 atom and keep the exciting stable and repeatable for 10 h, which is essential for Rydberg-mediated single-atom quantum information processing. This dual-laser frequency stabilization and transfer method can also be used in other high-resolution experiments in atomic physics, precision metrology, and molecular spectroscopy.