An Improved Implementation Approach for Quantum Phase Estimation on\n Quantum Computers

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