Recursive quantum detector tomography

TL;DR

This paper introduces a recursive quantum detector tomography method that efficiently reconstructs quantum operators using coherent states, significantly reducing complexity and improving robustness against noise.

Contribution

A novel recursive tomography technique that reconstructs quantum operators efficiently by focusing on diagonals and off-diagonals sequentially, reducing parameters needed.

Findings

Demonstrates efficiency and robustness of the method.

Successfully reconstructs a phase-sensitive optical detector.

Shows reduced complexity compared to traditional methods.

Abstract

Conventional tomographic techniques are becoming increasingly infeasible for reconstructing the operators of quantum devices of growing sophistication. We describe a novel tomographic procedure using coherent states which begins by reconstructing the diagonals of the operator, and then each successive off-diagonal in a recursive manner. Each recursion is considerably more efficient than reconstructing the operator in its entirety, and each successive recursion involves fewer parameters. We apply our technique to reconstruct the positive-operator-valued measure (POVM) corresponding to a recently developed coherent optical detector with phase sensitivity and number resolution. We discuss the effect of various parameters on the reconstruction accuracy. The results show the efficiency of the method and its robustness to experimental noise.