Fig. 1. Diagram of preparation of low-temperature atom sample. (a) The 671 nm MOT and the energy level of 2S-2P transition; (b) the 323 nm MOT and the energy level of 2S-3P transition. The atoms are successively trapped by 671 nm MOT and 323 nm MOT, and the 6×10⁷ atoms are obtained at the temperature of 40 μK finally

Fig. 2. Schematic diagrams and results of the state preparation for ⁶Li atoms. (a)(b) The schematic diagrams of state preparation by pure optical and combination with laser and radio frequency, respectively; (c)(d)(e) the atom distribution before state preparation, after state preparation by pure optical and combination with laser and radio frequency

Fig. 3. The optical path and energy level diagram of Raman beams in atom interferometer, and space-time trajectories of atoms in Ramsey-Bordé interferometers. (a) The σ⁺-π polarized crossed Raman beams,HWP and QWP are half wave plates and quarter wave plates, respectively, and PMT is a photomultiplier tube; (b) the energy levels and optical frequencies involved in magnetic insensitive Raman transitions; (c) the space-time trajectories of atoms in the up interferometry that ignores gravity; (d) the space-time trajectories of atoms in the low interferometry that ignores gravity, the solid and dashed lines represent the $\left|\mathrm{2}\right.〉$ state and $\left|\mathrm{5}\right.〉$ state of atoms, respectively, and the arrows represent the direction of effective moment which $\left|\mathrm{2}\right.〉$ state gets by pulses

Fig. 4. Interference signal of the ⁶Li atom interferometer. (a)-(d) The probability of the detecting of $\left|\mathrm{5}\right.〉$ state in four conjugated Ramsey Bordé interferometers,each point is the average value of three measurements with the same parameters; (e) closer inspection fringes at 1000-1100 μs under the parameters in Fig.4 (a), this high-frequency oscillation is due to the recoil frequency

Table 1. Relative uncertainty budgets for the measurement