Variational waveguide QED simulators

TL;DR

This paper explores how waveguide QED simulators, which use tunable-range interactions between quantum emitters, can enhance variational quantum algorithms by efficiently approximating ground states of quantum spin models, even under noise.

Contribution

It introduces the use of tunable-range interactions in waveguide QED simulators as a resource for developing more efficient variational quantum algorithms and ansätze.

Findings

Waveguide QED-based ansätze require fewer gates and parameters.

These ansätze accurately capture ground states of quantum critical models.

Potential noise resilience of waveguide QED variational methods.

Abstract

Waveguide QED simulators are analogue quantum simulators made by quantum emitters interacting with one-dimensional photonic band-gap materials. One of their remarkable features is that they can be used to engineer tunable-range emitter interactions. Here, we demonstrate how these interactions can be a resource to develop more efficient variational quantum algorithms for certain problems. In particular, we illustrate their power in creating wavefunction ans\"atze that capture accurately the ground state of quantum critical spin models (XXZ and Ising) with less gates and optimization parameters than other variational ans\"atze based on nearest-neighbor or infinite-range entangling gates. Finally, we study the potential advantages of these waveguide ans\"atze in the presence of noise. Overall, these results evidence the potential of using the interaction range as a variational parameter and place waveguide QED simulators as a promising platform for variational quantum algorithms.