Error Resilient Quantum Amplitude Estimation from Parallel Quantum Phase Estimation

TL;DR

This paper introduces a parallelization method for quantum phase and amplitude estimation algorithms that reduces circuit depth and significantly enhances error resilience, maintaining high probability of correct solutions even under high error rates.

Contribution

It presents a novel parallelization technique for quantum amplitude estimation that improves error resilience without increasing circuit depth.

Findings

Parallelization reduces quantum circuit depth to that of a single Grover operator.

The method significantly improves error resilience in amplitude estimation.

Correct solutions are obtained with high probability despite high error rates.

Abstract

We show how phase and amplitude estimation algorithms can be parallelized. This can reduce the gate depth of the quantum circuits to that of a single Grover operator with a small overhead. Further, we show that for quantum amplitude estimation, the parallelization can lead to vast improvements in resilience against quantum errors. The resilience is not caused by the lower gate depth, but by the structure of the algorithm. Even in cases with errors that make it impossible to read out the exact or approximate solutions from conventional amplitude estimation, our parallel approach provided the correct solution with high probability. The results on error resilience hold for the standard version and for low depth versions of quantum amplitude estimation. Methods presented are subject of a patent application [Quantum computing device: Patent application EP 21207022.1].