Pauli transfer matrix direct reconstruction: channel characterization without full process tomography

TL;DR

This paper introduces a more efficient method for quantum channel characterization that directly reconstructs the Pauli transfer matrix using fewer experimental configurations, reducing complexity compared to standard process tomography.

Contribution

It proposes a novel tomographic protocol that simplifies multiqubit channel characterization by directly relating output measurements to the Pauli transfer matrix, reducing experimental complexity.

Findings

Exponential reduction in experimental configurations compared to standard tomography

Maintains the same number of shots for each matrix element

Applicable to multiqubit quantum channels

Abstract

We present a tomographic protocol for the characterization of multiqubit quantum channels. We discuss a specific class of input states, for which the set of Pauli measurements at the output of the channel directly relates to its Pauli transfer matrix components. We compare our results to those of standard quantum process tomography, showing an exponential reduction in the number of different experimental configurations required by a single matrix element extraction, while keeping the same number of shots. This paves the way for more efficient experimental implementations, whenever a selective knowledge of the Pauli transfer matrix is needed. We provide several examples and simulations.