Implementing efficient selective quantum process tomography of superconducting quantum gates on IBM quantum experience

Akshay Gaikwad,Kavita Dorai,Arvind Arvind,Krishna Shende

doi:10.1038/s41598-022-07721-3

Akshay Gaikwad, Kavita Dorai + Show 2 more

Open Access

https://doi.org/10.1038/s41598-022-07721-3

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Abstract

The experimental implementation of selective quantum process tomography (SQPT) involves computing individual elements of the process matrix with the help of a special set of states called quantum 2-design states. However, the number of experimental settings required to prepare input states from quantum 2-design states to selectively and precisely compute a desired element of the process matrix is still high, and hence constructing the corresponding unitary operations in the lab is a daunting task. In order to reduce the experimental complexity, we mathematically reformulated the standard SQPT problem, which we term the modified SQPT (MSQPT) method. We designed the generalized quantum circuit to prepare the required set of input states and formulated an efficient measurement strategy aimed at minimizing the experimental cost of SQPT. We experimentally demonstrated the MSQPT protocol on the IBM QX2 cloud quantum processor and selectively characterized various two- and three-qubit quantum gates.

Highlights

The experimental implementation of selective quantum process tomography (SQPT) involves computing individual elements of the process matrix with the help of a special set of states called quantum 2-design states
We proposed a quantum circuit to efficiently implement the modified SQPT (MSQPT) protocol which reduces the experimental cost of performing standard SQPT
The system was prepared in a mixed state corresponding to all Pauli operators and the MSQPT protocol to perform element wise process tomography of two- and three-qubit quantum gates was successfully implemented

Summary

Introduction

The experimental implementation of selective quantum process tomography (SQPT) involves computing individual elements of the process matrix with the help of a special set of states called quantum 2-design states. The SQPT protocol is computationally less resourceintensive as compared to the standard QPT method, the number of experimental settings required to prepare the input states for computing a selected element of the process matrix is still quite high.

Results

Conclusion