  An efficient characterization of QND measurements is an important ingredient
towards certifying and improving the performance and scalability of quantum
processors. In this work, we introduce a parallel tomography of QND
measurements that addresses single- and two-qubit readout on a multi-qubit
quantum processor. We provide an experimental demonstration of the tomographic
protocol on a 7-qubit IBM-Q device, characterizing the quality of conventional
qubit readout as well as generalized measurements such as parity or
measurement-and-reset schemes. Our protocol reconstructs the Choi matrices of
the measurement processes, extracts relevant quantifiers -- fidelity, QND-ness,
destructiveness -- and identifies sources of errors that limit the performance
of the device for repeated QND measurements. We also show how to quantify
measurement cross-talk and use it to certify the quality of simultaneous
readout on multiple qubits.
