High Fidelity Trapped Ion Qubit Gate Operations with a Narrow-Linewidth Integrated Photonic Laser

We present the first high-fidelity (>99%) single qubit gates with trapped ions using an integrated photonic laser system comprised of an SBS laser locked to a high-Q coil resonator. We use this integrated laser to excite an ultra-narrow clock transition in ⁸⁸Sr⁺ trapped in a surface electrode trap without the use of a conventional cavity or second harmonic generation (SHG). We overcome residual thermal drift by using a clock feedback sequence to discipline the laser to the ion clock transition and interleave qubit control sequences.

 

We achieve Rabi oscillations that retain >99% population per inversion for rotations exceeding 10π, equivalent to single qubit gate fidelity of 99.7%. We also achieve narrow linewidth qubit spectroscopy with <1kHz full width at half-max. We can perform state preparation and measurement with 99.75% fidelity, perform resolved-sideband cooling below nbar=0.1, and measure a laser-limited coherence time of 329μs via Ramsey contrast decay measurement. These results light the way towards a monolithic, photonic integrated trapped ion platform for portable quantum computing and sensing.