2017/10/31 by Claudia Benedetti, Fahimeh Salari Sehdaran, Mohammad Hossein Zandi +2 · 2 citations
Computer Science · Mathematics · Physics and Astronomy · #Cutoff #Cutoff frequency #Mathematics #Optics #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum and electron transport phenomena #Quantum mechanics #Quantum state #Quantum system #Qubit #Statistical physics #quant-ph
paper · pdf · doi:10.1103/physreva.97.012126
published as Phys. Rev. A 97, 012126 (2018) · 8 pages, 5 figures, 1 table
openalex publication_date 2018/01/24 · arxiv created 2018/02/01 · arxiv updated 2018/02/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Quantum probing consists of suitably exploiting a simple, small, and controllable quantum system to characterize a larger and more complex system. Here, we address the estimation of the cutoff frequency of the Ohmic spectral density of a harmonic reservoir by quantum probes. To this aim, we address the use of single-qubit and two-qubit systems and different kinds of coupling with the bath of oscillators. We assess the estimation precision by the quantum Fisher information of the sole quantum probe as well as the corresponding quantum signal-to-noise ratio. We prove that, for most of the values of the Ohmicity parameter, a simple probe such as a single qubit is already optimal for the precise estimation of the cutoff frequency. Indeed for those values, upon considering a two-qubit probe either in a Bell or in separable state, we do not find improvement to the estimation precision. However, we also showed that there exist few conditions where employing two qubits in a Bell state interacting with a common bath is more suitable for precisely estimating the cutoff frequency.