Effects of Cosine Tapering Window on Quantum Phase Estimation

Understand

We provide a modification to the quantum phase estimation algorithm (QPEA) inspired on classical windowing methods for spectral density estimation.

• From this modification we obtain an upper bound in the cost that implies a cubic improvement with respect to the algorithm's error rate.
• Numerical evaluation of the costs also demonstrates an improvement.
• Moreover, with similar techniques, we detail an iterative projective measurement method for ground state preparation that gives an exponential improvement over previous bounds using QPEA.