2025-10-28 ロードアイランド大学(URI)
＜関連情報＞
- https://www.uri.edu/news/2025/10/study-by-uri-physics-professor-may-lead-to-improved-networked-quantum-sensing/
- https://journals.aps.org/prl/abstract/10.1103/jkjj-3gvb#s1
任意の重みを持つハイゼンベルグ限界連続変数分散量子計測 Heisenberg-Limited Continuous-Variable Distributed Quantum Metrology with Arbitrary Weights
Wenchao Ge and Kurt Jacobs
Physical Review Letters Published: 2 September, 2025
DOI: https://doi.org/10.1103/jkjj-3gvb
Abstract
Distributed quantum metrology (DQM) enables the estimation of global functions of distributed parameters beyond the capability of separable sensors. Continuous-variable DQM involves using a linear network with at least one nonclassical input. Here, we fully elucidate the structure of linear networks with two nonvacuum inputs, which allows us to prove a number of fundamental properties of continuous-variable DQM. While measuring the sum of parameters at the Heisenberg limit can be achieved with a single nonvacuum input, we show that two inputs, one of which can be classical, are required to measure an arbitrary linear combination of parameters and an arbitrary global function of the parameters. We obtain a universal and tight upper bound on the sensitivity of DQM networks with two inputs, and completely characterize the properties of the nonclassical input required to obtain a quantum advantage. This reveals that a wide range of nonclassical states makes this possible, including a squeezed vacuum. We also show that, for a class of nonclassical inputs, local photon number detection will achieve the maximum sensitivity. Finally we show that a general DQM network has two distinct regimes. The first achieves Heisenberg scaling. In the second the nonclassical input is much weaker than the coherent input, nevertheless providing a multiplicative enhancement to the otherwise classical sensitivity.
