Goldilocks Probes for Noisy Interferometry via Quantum Annealing to Criticality

TL;DR

This paper introduces a novel quantum annealing-based method to generate robust interferometric probes near criticality, achieving enhanced phase estimation precision in noisy environments with linear adiabatic complexity.

Contribution

It demonstrates a new approach to creating quantum probes using annealing near critical points, surpassing traditional models in robustness and efficiency.

Findings

Goldilocks probes exhibit enhanced phase estimation in noisy environments.

Probe preparation time scales linearly with system size N.

Asymptotic saturation of quantum precision bounds in realistic noise conditions.

Abstract

Quantum annealing is explored as a resource for quantum information beyond solution of classical combinatorial problems. Envisaged as a generator of robust interferometric probes, we examine a Hamiltonian of $N>> 1$ uniformly-coupled spins subject to a transverse magnetic field. The discrete many-body problem is mapped onto dynamics of a single one-dimensional particle in a continuous potential. This reveals all the qualitative features of the ground state beyond typical mean-field or large classical spin models. It illustrates explicitly a graceful warping from an entangled unimodal to bi-modal ground state in the phase transition region. The transitional `Goldilocks' probe has a component distribution of width $N^{2/3}$ and exhibits characteristics for enhanced phase estimation in a decoherent environment. In the presence of realistic local noise and collective dephasing, we find this probe state asymptotically saturates ultimate precision bounds calculated previously. By reducing the transverse field adiabatically, the Goldilocks probe is prepared in advance of the minimum gap bottleneck, allowing the annealing schedule to be terminated `early'. Adiabatic time complexity of probe preparation is shown to be linear in $N$