Quantum Amplitude-Phase Judgment Circuits for Full Quantization Algorithms

Quantum algorithms are a crucial component of quantum computing. One key open question in this field is whether quantum algorithms (QAs) can be fully executed on a quantum computer. Many QAs currently rely on classical computers to evaluate conditional statements that quantum systems alone cannot assess. This dependency necessitates information transmission between quantum and classical systems, thus imposing performance limitations. To enable autonomous conditional evaluations on quantum systems, a quantum amplitude-phase judgment circuit (QAPJC), comprising primarily quantum inequality judgment circuits and equality judgment logic blocks, is proposed. This configuration achieves conditional judgment on quantum computers while imparting physical significance to the judgment process. The feasibility of the circuits is verified on a superconducting quantum computer. Comparative experiments confirm that QAPJC preserves the original performance of QAs while demonstrating the inherent advantages of quantum computing. This circuit can implement logic judgment functions akin to classical circuits and serve as a subroutine for various QAs, promoting their implementation in the noisy intermediate-scale quantum (NISQ) era.