Subspace Leakage Error Randomized Benchmarking of Mølmer-Sørensen Gates
Authors
R. T. Sutherland
A. C. Hughes
J. P. Marceaux
H. M. Knaack
C. M. Löschnauer
R. Srinivas
Abstract
We demonstrate a new technique that adapts single-qubit randomized benchmarking to two-qubit Mølmer-Sørensen gates. We use the controllable gate phase to generate Cliffords that act on a two-state subspace, enabling benchmarking of two-qubit gates without single-qubit operations. In addition to quantifying the gate infidelity, the protocol provides valuable information about the type of error by distinguishing between those that conserve the two-state subspace and those that result in leakage out of it. We demonstrate the protocol for calibrating and validating all-electronic maximally entangling gates in a trapped-ion quantum computer, achieving a two-qubit gate error of $2.6 (2)\times10^{-4}$.
