Chang HuangShijie ChaiShau-Yu Lan2025-01-202025-01-202021-01-06https://scholars.lib.ntu.edu.tw/handle/123456789/724906We utilize the dark state in a Λ-type three-level system to cool an ensemble of Rb85 atoms in an optical lattice [Morigi, Phys. Rev. Lett. 85, 4458 (2000)PRLTAO0031-900710.1103/PhysRevLett.85.4458]. The common suppression of the carrier transition of atoms with different vibrational frequencies allows them to reach a subrecoil temperature of 100 nK after being released from the optical lattice. A nearly zero vibrational quantum number is determined from the time-of-flight measurements and adiabatic expansion process. The features of sideband cooling are examined in various parameter spaces. Our results show that dark-state sideband cooling is a simple and compelling method for preparing a large ensemble of atoms into their vibrational ground state of a harmonic potential and can be generalized to different species of atoms and molecules for studying ultracold physics that demands recoil temperature and below.journal article10.1103/physreva.103.013305