# High-fidelity quantum tomography with imperfect measurements

## TL;DR

This paper presents an improved quantum process tomography method that accounts for measurement imperfections, using identity gate tomography to enhance fidelity in superconducting quantum processors.

## Contribution

It introduces a novel approach to estimate measurement errors via identity gate tomography, significantly improving quantum process fidelity.

## Key findings

- Fidelity for Hadamard increased from 89% to 98%.
- Fidelity for CNOT increased from 77% to 95%.
- Method successfully tested on IBM superconducting quantum processor.

## Abstract

In the current work we address the problem of quantum process tomography (QPT) in the case of imperfect preparation and measurement of the states which are used for QPT. The fuzzy measurements approach which helps us to efficiently take these imperfections into account is considered. However, to implement such a procedure one should have a detailed information about the errors. An approach for obtaining the partial information about them is proposed. It is based on the tomography of the ideal identity gate. This gate could be implemented by performing the measurement right after the initial state preparation. By using the result of the identity gate tomography we were able to significantly improve further QPT procedures. The proposed approach has been tested experimentally on the IBM superconducting quantum processor. As a result, we have obtained an increase in fidelity from 89% to 98% for Hadamard transformation and from 77% to 95% for CNOT gate.