27 Mar 2024 | Elisa Bäumer, Vinay Tripathi, Alireza Seif, Daniel Lidar, Derek S. Wang
This paper presents a study on the quantum Fourier transform (QFT) using dynamic circuits, demonstrating the advantages of dynamic quantum circuits over traditional unitary circuits. The research is conducted on IBM's superconducting quantum hardware, showing that dynamic circuits significantly reduce resource requirements for the QFT+M subroutine, which is a core component of quantum algorithms like Shor's algorithm and quantum phase estimation. The key advantage of dynamic circuits is their ability to use mid-circuit measurements and feed-forward operations, which allows for a reduction in the number of two-qubit gates from O(n²) to O(n) without connectivity constraints.
The study introduces a method for certifying process fidelity, which is crucial for evaluating the performance of quantum circuits. This method enables the efficient verification of the fidelity of noisy unitary operations followed by measurements. Additionally, the paper presents a dynamical decoupling protocol called feed-forward-compensated dynamical decoupling (FC-DD), which suppresses errors during mid-circuit measurements and feed-forward operations. This protocol significantly improves the fidelity of the QFT+M implementation, achieving fidelities greater than 1% for up to 37 qubits, which is a substantial improvement over previous results.
The results show that dynamic circuits outperform traditional unitary circuits in terms of process fidelity, especially when error suppression techniques like FC-DD are applied. The study also highlights the potential of dynamic circuits for optimizing and enabling larger-scale quantum algorithms. The implementation of FC-DD in dynamic circuits allows for more efficient error suppression, leading to higher fidelity and better performance in quantum computations. The findings demonstrate the practical benefits of dynamic circuits in quantum computing, particularly in reducing resource requirements and improving the fidelity of quantum algorithms.This paper presents a study on the quantum Fourier transform (QFT) using dynamic circuits, demonstrating the advantages of dynamic quantum circuits over traditional unitary circuits. The research is conducted on IBM's superconducting quantum hardware, showing that dynamic circuits significantly reduce resource requirements for the QFT+M subroutine, which is a core component of quantum algorithms like Shor's algorithm and quantum phase estimation. The key advantage of dynamic circuits is their ability to use mid-circuit measurements and feed-forward operations, which allows for a reduction in the number of two-qubit gates from O(n²) to O(n) without connectivity constraints.
The study introduces a method for certifying process fidelity, which is crucial for evaluating the performance of quantum circuits. This method enables the efficient verification of the fidelity of noisy unitary operations followed by measurements. Additionally, the paper presents a dynamical decoupling protocol called feed-forward-compensated dynamical decoupling (FC-DD), which suppresses errors during mid-circuit measurements and feed-forward operations. This protocol significantly improves the fidelity of the QFT+M implementation, achieving fidelities greater than 1% for up to 37 qubits, which is a substantial improvement over previous results.
The results show that dynamic circuits outperform traditional unitary circuits in terms of process fidelity, especially when error suppression techniques like FC-DD are applied. The study also highlights the potential of dynamic circuits for optimizing and enabling larger-scale quantum algorithms. The implementation of FC-DD in dynamic circuits allows for more efficient error suppression, leading to higher fidelity and better performance in quantum computations. The findings demonstrate the practical benefits of dynamic circuits in quantum computing, particularly in reducing resource requirements and improving the fidelity of quantum algorithms.