摘要
We report the experimental realization of quantum degenerate Fermi gases of87Sr atoms under controlled 10-and dual-nuclear-spin configurations.Based on laser cooling and evaporative cooling,we achieve an ultracold Fermi gas of 10^(5)atoms equally distributed over 10 spin states,with a temperature of T/T_(F)=0.21.We further prepare a dual-spin gas by optically pumping atoms to the m_(F)=9/2 and m_(F)=7/2 states and observe a slightly lower T/T_(F)than that for a 10-spin gas under the same trapping condition,showing efficient evaporative cooling under a decreasing number N of spin states(N≥2)despite the increasing importance of Pauli exclusion.Given that rethermalization becomes less efficient with N approaching unity,we evaporatively cool an almost polarized gas to 130 nK.The simple and efficient preparation of ultracold Fermi gases of^(87)Sr with tunable spin configurations provides a first step towards engineering topological quantum systems.
基金
Supported by the National Key Research and Development Program of China under Grant Nos 2016YFA0300901 and 2018YFA0305601
the National Natural Science Foundation of China under Grant No 11874073
the International Center for Quantum Materials of Peking University
