Quantum search in many-body interacting system with long-range interaction

TL;DR

This paper investigates three physical systems with long-range atom-atom interactions for quantum search, demonstrating near-optimal performance without dissipation and robustness in waveguide-QED and cavity-QED systems even with dissipation.

Contribution

It identifies physical systems capable of implementing quantum search with long-range interactions and analyzes their performance considering dissipation effects.

Findings

All three systems can achieve near-optimal quantum search without dissipation.

Waveguide-QED and cavity-QED systems maintain high success probabilities despite dissipation.

Spectral gap enhancement reduces search time and dissipation effects.

Abstract

Continuous-time quantum walks provide an alternative method for quantum search problems. Most of the earlier studies confirmed that quadratic speedup exists in some synthetic Hamiltonians, but whether there is quadratic speedup in real physical systems is elusive. Here, we investigate three physical systems with long-range atom-atom interaction which are possible good candidates for realizing the quantum search, including one-dimensional atom arrays either trapped in an optical lattice or coupled to waveguide near band edge or dispersively coupled to a good cavity. We find that all three systems can provide near-optimal quantum search if there is no dissipation. However, if the dissipation is considered only the latter two systems (i.e., waveguide-QED and cavity-QED systems) can still have high success probabilities because the latter two systems can significantly enhance the atom-atom interaction even if they are far apart and the spectra gap can be much larger which can reduce the search time and the effects of dissipation significantly. Our studies here can provide helpful instructions for realizing quantum search in real physical systems in the noisy intermediate-scale quantum era.