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

We demonstrate the implementation of a spin qubit with a single 40Ca+ ion in a micro ion trap. The qubit is encoded in the Zeeman ground state levels mJ = +1/2 and mJ = −1/2 of the S1/2 state of the ion. We show sideband cooling close to the vibrational ground state and demonstrate the initialization and readout of the qubit levels with 99.5% efficiency. We employ a Raman transition close to the S1/2–P1/2 resonance for coherent manipulation of the qubit. We observe single qubit rotations with 96% fidelity and gate times below 5 µs. Rabi oscillations on the blue motional sideband are used to extract the phonon number distribution. The dynamics of this distribution is analysed to deduce the trap-induced heating rate of 0.3(1) phonons ms−1.