2016/07/31 by Dario Tamascelli, D. Tamascelli, Claudia Benedetti +5 · 1 citation
Computer Science · Mathematics · Physics and Astronomy · #Algorithm #Bayesian probability #Characterization (materials science) #Computer science #Coupling (piping) #Estimator #Feynman diagram #Materials science #Mathematics #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum mechanics #Qubit #Statistical physics #Statistics #quant-ph
paper · pdf · doi:10.1103/physreva.94.042129
published as Phys. Rev. A 94, 042129 (2016) · 8 pages, 5 figures
openalex publication_date 2016/10/26 · arxiv created 2016/11/16 · arxiv updated 2016/11/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We address the characterization of qubit chains and assess the performances of local measurements compared to those provided by Feynman probes, i.e., nonlocal measurements realized by coupling a single-qubit register to the chain. We show that local measurements are suitable to estimate small values of the coupling and that a Bayesian strategy may be successfully exploited to achieve optimal precision. For larger values of the coupling Bayesian local strategies do not lead to a consistent estimate. In this regime, Feynman probes may be exploited to build a consistent Bayesian estimator that saturates the Cram'er-Rao bound, thus providing an effective characterization of the chain. Finally, we show that ultimate bounds to precision, i.e., saturation of the quantum Cram'er-Rao bound, may be achieved by a two-step scheme employing Feynman probes followed by local measurements.