# Quantum Phase Estimation: More Qubits, More Accuracy

## Determine Phase of an Eigenvector of a Unitary Operator

Quantum Phase Estimation (QPE) is an algorithm that’s used to estimate the phase (or eigenvalue) of an eigenvector of a unitary operator. Since this post will use many important concepts discussed in the Quantum Fourier Transform post, please check it for a review. What you can…