  As a variety of quantum computing models and platforms become available,
methods for assessing and comparing the performance of these devices are of
increasing interest and importance. Despite being built of the same fundamental
computational unit, radically different approaches have emerged for
characterizing the performance of qubits in gate-based and quantum annealing
computers, limiting and complicating consistent cross-platform comparisons. To
fill this gap, this work proposes a single-qubit protocol (Q-RBPN) for
measuring some basic performance characteristics of individual qubits in both
models of quantum computation. The proposed protocol scales to large quantum
computers with thousands of qubits and provides insights into the distribution
of qubit properties within a particular hardware device and across families of
devices. The efficacy of the Q-RBPN protocol is demonstrated through the
analysis of more than 300 gate-based qubits spanning eighteen machines and 2000
annealing-based qubits from one machine, revealing some unexpected differences
in qubit performance. Overall, the proposed Q-RBPN protocol provides a new
platform-agnostic tool for assessing the performance of a wide range of
emerging quantum computing devices.
