Noise-robust quantum sensing via optimal multi-probe spectroscopy

TL;DR

This paper introduces advanced quantum sensing techniques that utilize multi-probe spectroscopy, optimal control, and entanglement to achieve noise-robust environmental spectral characterization.

Contribution

It presents novel estimation strategies combining filter orthogonalization, optimal control, and multi-qubit entanglement for robust quantum noise spectroscopy.

Findings

Strategies are robust against finite measurement precision.

Methods effectively characterize classical and quantum dephasing environments.

Robustness is demonstrated under various noise conditions.

Abstract

The dynamics of quantum systems are unavoidably influenced by their environment and in turn observing a quantum system (probe) can allow one to measure its environment: Measurements and controlled manipulation of the probe such as dynamical decoupling sequences as an extension of the Ramsey interference measurement allow to spectrally resolve a noise field coupled to the probe. Here, we introduce fast and robust estimation strategies for the characterization of the spectral properties of classical and quantum dephasing environments. These strategies are based on filter function orthogonalization, optimal control filters maximizing the relevant Fisher Information and multi-qubit entanglement. We investigate and quantify the robustness of the schemes under different types of noise such as finite-precision measurements, dephasing of the probe, spectral leakage and slow temporal fluctuations of the spectrum.