Realization of highly isolated stable few-spin systems based on alkaline-earth fermions

Few-level systems consisting of a certain number of spin states have provided the basis of a wide range of cold atom researches. However, more developments are still needed for better preparation of isolated few-spin systems. In this work, we demonstrate a highly nonlinear spin-discriminating (HNSD) method for isolating an arbitrary few-level manifold out of a larger total number of spin ground states in fermionic alkaline-earth atoms. With this method, we realize large and tunable energy shifts for unwanted spin states while inducing negligible shifts for the spin states of interest, which leads to a highly isolated few-spin system under minimal perturbation. Furthermore, the isolated few-spin system exhibits a long lifetime on the hundred-millisecond scale. Using the HNSD method, we demonstrate a characteristic Rabi oscillation between the two states of an isolated two-spin Fermi gas. Our method has wide applicability for realizing long-lived two-spin or high-spin quantum systems based on alkaline-earth fermions.