Coherent manipulation of a⁴⁰Ca⁺spin qubit in a micro ion trap

Abstract

We demonstrate the implementation of a spin qubit with a single Ca ion in a\nmicro ion trap. The qubit is encoded in the Zeeman ground state levels mJ=+1/2\nand mJ=-1/2 of the S1/2 state of the ion. We show sideband cooling close to the\nvibrational ground state and demonstrate the initialization and readout of the\nqubit levels with 99.5% efficiency. We employ a Raman transition close to the\nS1/2 - P1/2 resonance for coherent manipulation of the qubit. We observe single\nqubit rotations with 96% fidelity and gate times below 5mus. Rabi oscillations\non the blue motional sideband are used to extract the phonon number\ndistribution. The dynamics of this distribution is analyzed to deduce the\ntrap-induced heating rate of 0.3(1) phonons/ms.\n