Solving generalized eigenvalue problems by ordinary differential equations on a quantum computer
Changpeng Shao, Jinpeng Liu · Proceedings of the Royal Society A Mathematical Physical and Engineering Sciences · 2022
Many eigenvalue problems arising in practice are often of the generalized form A x = λ B x . One particularly important case is symmetric, namely A , B are Hermitian and B is positive definite. The standard algorithm for solving this class of eigenvalue problems is to reduce them to Hermitian eigenvalue problems. For a quantum computer, quantum phase estimation is a useful technique to solve Hermitian eigenvalue problems. In this work, we propose a new quantum algorithm for symmetric generalized eigenvalue problems using ordinary differential equations. The algorithm has lower complexity than the standard one based on quantum phase estimation. Moreover, it works for a wider case than symmetric: B is invertible, B − 1 A is diagonalizable and all the eigenvalues are real.