High-Fidelity Manipulation of the Quantized Motion of a Single Atom via Stern–Gerlach Splitting**Supported by the National Key Research and Development Program of China (Grant Nos. 2017YFA0304501, 2016YFA0302800 and 2016YFA0302002), the Key Research Program of Frontier Science of the Chinese Academy of Sciences (CAS) (Grant No. ZDBSLY- SLH012), the National Natural Science Foundation of China (Grant No. 11774389), the Strategic Priority

Abstract

We demonstrate high-fidelity manipulation of the quantized motion of a single 87Rb atom in an optical tweezer via microwave couplings induced by Stern–Gerlach splitting. The Stern–Gerlach splitting is mediated by polarization gradient of a strongly focused tweezer beam that functions as fictitious magnetic field gradient. The spatial splitting removes the orthogonality of the atomic spatial wavefunctions, thus enables the microwave couplings between the motional states. We obtain coherent Rabi oscillations for up to third-order sideband transitions, in which a high fidelity of larger than 0.99 is obtained for the spin-flip transition on the first order sideband after subtraction of the state preparation and detection error. The Stern–Gerlach splitting is measured at a precision of better than 0.05 nm. This work paves the way for quantum engineering of motional states of single atoms, and may have wide applications in few body physics and ultracold chemistry.