QSCOUT: A versatile, low-level trapped-ion quantum testbed

Sandia National Laboratories is home to the Quantum Scientific Computing Open User Testbed (QSCOUT), a low-level quantum computing testbed based on trapped ions. As part of the DOE ASCR Quantum Testbed Program, QSCOUT aims to offer transparency and versatility in exploring quantum algorithms on a noisyintermediate- scale quantum (NISQ) system. Distinct from many commercial platforms, QSCOUT allows users access at a variety of levels within the software stack as deep as pulse-level control. Our all-to-all connected qubit register, a chain of Yb-171 ions, is hosted by a microfabricated surface-electrode electrode trap, and gates are realized via individually addressed optical Raman transitions. In particular, QSCOUT offers full parameterization of the two-qubit Mølmer-Sørensen (MS) gate, which has been crucial to a number of recent user collaborations. Here, I will discuss the empirical realization, error sources, and the frequency robustness of our continuously parameterized MS gate, as well as a recent effort to mitigate crosstalk from individual addressing beams. Combining these efforts and in collaboration with the Quantum Software team at Infleqtion (formerly University of Chicago spinout Super.tech), we develop and study noise-aware compilations focused on the continuously parameterized MS gates, including swap mirroring and gate ranking, to realize distinct improvements in system performance. To conclude, I will present a roadmap of future planned developments to broaden QSCOUT’s offerings, including mid-circuit measurements and multi-qubit entangling gates.