The invention belongs to the technical field of
quantum machine learning, and discloses a selectable accurate
quantum principal component analysis method and application, wherein based on a
quantum singular value threshold
decomposition algorithm, compared with traditional quantum
principal component analysis, the flexibility is high, main components, namely main characteristic value characteristic vectors, are output by controlling thresholds, and all components, namely all eigenvalue eigenvectors, can be output, and compared with the previous
improved algorithm, the
algorithm reduces the number of quantum gates in the parallel direction, and the result is more accurate. According to the invention, the accurate quantum
principal component analysis algorithm selected by the invention mainly comprises seven steps of inputting a
covariance matrix
quantum state, extracting a characteristic value through phase
estimation, converting the characteristic value, performing controlled overturning, performing inverse transformation, measuring, extracting and screening the characteristic value through phase
estimation, and finally outputting the characteristic value greater than a given threshold value and a corresponding characteristic vector; and the method can be used as a
subroutine of other algorithms in the field of quantum
machine learning, and the execution efficiency of the wholealgorithm is improved.