Quantum tomography of noisy ion-based qudits

TL;DR

This paper proposes a robust quantum tomography protocol for ion-based qudits that minimizes measurement operations and accounts for errors, significantly improving accuracy in practical quantum computing diagnostics.

Contribution

It introduces a measurement protocol with minimal quantum operations and methods to identify and correct state preparation and measurement errors in ion-based qudits.

Findings

A measurement protocol with no more than one quantum operation per measurement circuit.

The protocol is more error-resistant than mutually unbiased bases measurements.

Methods to determine and correct initialization and readout errors.

Abstract

Quantum tomography makes it possible to obtain comprehensive information about certain logical elements of a quantum computer. In this regard, it is a promising tool for debugging quantum computers. The practical application of tomography, however, is still limited by systematic measurement errors. Their main source are errors in the quantum state preparation and measurement procedures. In this work, we investigate the possibility of suppressing these errors in the case of ion-based qudits. First, we will show that one can construct a quantum measurement protocol that contains no more than a single quantum operation in each measurement circuit. Such a protocol is more robust to errors than the measurements in mutually unbiased bases, where the number of operations increases in proportion to the square of the qudit dimension. After that, we will demonstrate the possibility of determining and accounting for the state initialization and readout errors. Together, the measures described can significantly improve the accuracy of quantum tomography of real ion-based qudits.