Speaker
Description
We describe an agile microwave synthesis system devised of an ultra-low phase-noise cryogenic sapphire oscillator (CSO) that serves as a master clock for a ytterbium ion (Yb+) qubit. We report a 10X improvement of qubit coherence time from 0.9 to 8.7 seconds and single-qubit quantum gates with errors of 1.6e-6 achieved with the synthesis system. Using a filter function approach [1], we find evidence that the precious coherence of 0.9 seconds was limited by the phase noise of a precision-grade commercially off-the-shelve microwave synthesizer [1]. Furthermore, we also leverage the agility of the microwave synthesis system to demonstrate a Bayesian learning algorithm that can autonomously design informationally-optimised control pulses to identify and calibrate quantitative dynamical models to characterize a trapped-ion system. We experimentally demonstrate that the new algorithm exceeds the precision of conventional calibration methods with few samples [2].
References:
[1] H. Ball, W. Oliver, M. Biercuk. (2016). The role of master clock stability in quantum information processing npj Quantum Information 2(1), 16033. https://dx.doi.org/10.1038/npjqi.2016.33
[2] T. M. Stace, J. Chen, L. Li, V. S. Perunicic, A. R. R. Carvalho, M. R. Hush, C. H. Valahu, T. R. Tan, M. J. Biercuk. (2022). Optimised Bayesian system identification in quantum devices. arXiv:2211.09090. https://arxiv.org/abs/2211.09090
