Efficient reconstruction, benchmarking and validation of cross-talk models in readout noise in near-term quantum devices

Understand

Readout errors contribute significantly to the overall noise affecting present-day quantum computers.

• However, the complete characterization of generic readout noise is infeasible for devices consisting of a large number of qubits.
• Here we introduce an appropriately tailored quantum detector tomography protocol, the so called Quantum Detector Overlapping Tomography, which enables efficient characterization of $k-$local cross-talk effects in the readout noise as the sample complexity of the protocol scales logarithmically with the total number of qubits.
• We show that QDOT data provides information about suitably defined reduced POVM operators, correlations and coherences in the readout noise, as well as allows to reconstruct the correlated clusters and neighbours readout noise model.