Realization and Calibration of Continuously Parameterized Two-Qubit Gates on a Trapped-Ion Quantum Processor

Journal Article · Mon Aug 18 00:00:00 EDT 2025 · IEEE Transactions on Quantum Engineering

DOI:https://doi.org/10.1109/TQE.2025.3600216· OSTI ID:2589626

Yale, Christopher Gordon ^[1]; Burch, Ashlyn Damaris ^[1]; Chow, Matthew Nickolas Helson ^[2]; Ruzic, Brandon P. ^[1]; Lobser, Daniel S. ^[1]; McFarland, Brian K. ^[1]; Revelle, Melissa C. ^[1]; Clark, Susan Marie ^[1]

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1. Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
2. Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States)

Continuously parameterized two-qubit gates are a key feature of state-of-the-art trapped-ion quantum processors, as they have favorable error scalings and show distinct improvements in circuit performance over more restricted maximally entangling gatesets. In this work, we provide a comprehensive and pedagogical discussion on how to practically implement these continuously parameterized Mølmer–Sørensen gates on the Quantum Scientific Computing Open User Testbed, a low-level trapped-ion processor. To generate the arbitrary entangling angles, θ, we simply scale the amplitude of light used to generate the entanglement. However, doing so requires careful consideration of amplifier saturation as well as the variable light shifts that result. As such, we describe a method to calibrate and cancel the dominant fourth-order effects, followed by a dynamic virtual phase advance during the gate to cancel any residual light shifts, and find a linear scaling between θ and the residual light shift. Once we have considered and calibrated these effects, we demonstrate performance improvement with decreasing θ. Finally, we describe nuances of hardware control to transform the XX-type interaction of the arbitrary-angle Mølmer–Sørensen gate into a phase-agnostic and crosstalk-mitigating ZZ interaction.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR); USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program
• Grant/Contract Number: NA0003525
• OSTI ID: 2589626
• Report Number(s): SAND--2025-12057J; 1776933
• Journal Information: IEEE Transactions on Quantum Engineering, Journal Name: IEEE Transactions on Quantum Engineering Journal Issue: 1 Vol. 6; ISSN 2689-1808
• Publisher: Institute of Electrical and Electronics Engineers (IEEE)
• Country of Publication: United States
• Language: English