Characterization and mitigation of axial-motion induced noise on trapped ions using quantum noise spectroscopy

As quantum computing devices grow in capability, it is important to develop characterization techniques to study the noise on real machines at all scales. One such technique that is particularly well-suited to informing low-level hardware changes is quantum noise spectroscopy (QNS). In this work we use QNS to drive improvements to a trapped-ion quantum computer at the physical hardware calibration level. Using the ‘SineLobe’ spectroscopy technique (Maloney et al. 2022), we find that our leading source of noise stems from axial motion which causes the ion to experience the spatial inhomogeneity of the tightly-focused individual addressing beam. However, we demonstrate that by choosing the appropriate ion-beam position, we can strongly mitigate this noise source. We further use QNS to characterize the realized improvements on the Quantum Scientific Computing Open User Testbed (QSCOUT) device by using this updated calibration.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. SAND2024-00483A