Preparation of a two-state mixture of ultracold fermionic atoms with balanced population subject to the unstable magnetic field* *Project supported by the National Key Research and Development Program of China (Grant Nos. 2016YFA0301602 and 2018YFA0307601), the National Natural Science Foundation of China (Grant Nos. 12034011, 92065108, 11704234, 11804203, 11974224, 12022406, and 12004229), and the Fund for Shanxi “1331 Project” Key

Abstract

We report a novel method to prepare a mixture of 40K Fermi gas having an equal population of the two ground magnetic spin states confined in an optical dipole trap, in the presence of an noisy quantization (magnetic) field. We realize the equal population mixture by applying a series of RF pulses. We observe the dependence of the population distribution between two spin states on the number of the applied RF pulses and find that the decoherence effects leading to the population fluctuations are overcome by the high number of RF pules. Our demonstrated technique can be potentially used in the precision measurement experiments with ultracold gases in noisy environments.