Simulation of a feedback-based algorithm for quantum optimization for a realistic neutral atom system with an optimized small-angle controlled-phase gate

TL;DR

This paper demonstrates a feedback-based quantum optimization algorithm, FALQON, implemented with an optimized small-angle controlled-phase gate on a neutral atom system, showing improved performance over CZ gates for Max-Cut problems.

Contribution

It introduces a scheme for implementing an optimized small-angle controlled-phase gate tailored to neutral atom systems for FALQON, enhancing quantum optimization performance.

Findings

FALQON with small-angle controlled-phase gates outperforms CZ gates in Max-Cut.

The approach simplifies quantum circuit complexity for FALQON.

Potential for experimental realization of near-term quantum algorithms with neutral atoms.

Abstract

In contrast to the classical optimization process required by the quantum approximate optimization algorithm, FALQON, a feedback-based algorithm for quantum optimization [A. B. Magann {\it et al.,} {\color{blue}Phys. Rev. Lett. {\bf129}, 250502 (2022)}], enables one to obtain approximate solutions to combinatorial optimization problems without any classical optimization effort. In this study, we leverage the specifications of a recent experimental platform for the neutral atom system [Z. Fu {\it et al.,} {\color{blue}Phys. Rev. A {\bf105}, 042430 (2022)}] and present a scheme to implement an optimally tuned small-angle controlled-phase gate. By examining the 2- to 4-qubit FALQON algorithms in the Max-Cut problem and considering the spontaneous emission of the neutral atomic system, we have observed that the performance of FALQON implemented with small-angle controlled-phase gates exceeds that of FALQON utilizing CZ gates. This approach has the potential to significantly simplify the logic circuit required to simulate FALQON and effectively address the Max-Cut problem, which may pave a way for the experimental implementation of near-term noisy intermediate-scale quantum algorithms with neutral-atom systems.