An Improved Implementation Approach for Quantum Phase Estimation on Quantum Computers

TL;DR

This paper investigates the challenges of implementing quantum phase estimation on noisy intermediate-scale quantum (NISQ) devices and proposes modifications to improve accuracy by reducing certain quantum gates.

Contribution

The paper introduces a modified quantum phase estimation approach tailored for NISQ devices, reducing controlled rotation gates to enhance phase accuracy.

Findings

Accuracy constrained by NISQ hardware characteristics

Modified approach improves phase estimation precision

Experimental validation on IBM Q devices

Abstract

Quantum phase estimation (QPE) is one of the core algorithms for quantum computing. It has been extensively studied and applied in a variety of quantum applications such as the Shor's factoring algorithm, quantum sampling algorithms and the calculation of the eigenvalues of unitary matrices. The QPE algorithm has been combined with Kitaev's algorithm and the inverse quantum Fourier transform (IQFT) which are utilized as a fundamental component of such quantum algorithms. In this paper, we explore the computational challenges of implementing QPE algorithms on noisy intermediate-scale quantum (NISQ) machines using the IBM Q Experience (e.g., the IBMQX4, 5-qubit quantum computing hardware platform). Our experimental results indicate that the accuracy of finding the phase using these QPE algorithms is severely constrained by the NISQ computer's physical characteristics such as coherence time and error rates. To mitigate these physical limitations, we propose implementing a modified solution by reducing the number of controlled rotation gates and phase shift operations, thereby increasing the accuracy of the finding phase in near-term quantum computers.