Experimental reconstruction of all correlated error rates on a 16 qubit device.

Recent results by Flammia and Wallman have shown how to reliably and efficiently characterize Pauli channels on intermediate and large-scale quantum devices. Here we leverage those results to give a complete, efficient, and high-precision, characterization of IBM's online 16 qubit device. Using experimental results from the device we obtain and present complete information about the correlated error rates across the device, comparing device characteristics when qubits are operated in single qubit mode and with qubit-to-qubit interactions enabled. The protocol we use obtains multiplicative precision and robustness to SPAM errors by using techniques originating from randomized benchmarking, and it can be executed on all current NISQ devices. The protocol is easy to implement, involving just computational basis state preparation and measurement together with only one-qubit Clifford gates. We show how this protocol can be scaled up to even larger devices of 100 or even 1000 qubits.