发表机构
Harish-Chandra Research Institute; Homi Bhabha National Institute（哈里什·钱德拉研究所; 霍米·巴巴国立研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究以Aubry-André-Harper模型为对象，发现噪声与系统尺寸相互作用会限制量子费舍尔信息的量子增强标度，过大的探针尺寸会破坏计量学量子优势。
AI 中文摘要
局域化-去局域化跃迁近期被提出用于构建一类高效的量子多体临界传感器。本研究聚焦于支持在位势有限强度下发生局域化-去局域化跃迁的Aubry-André-Harper模型，详细考察此类器件的计量学性能。我们识别出由噪声与系统尺寸相互作用驱动的计量学量子-经典 crossover，其中量子费舍尔信息的量子增强标度仅在有限的、依赖噪声的特征系统尺寸内持续存在。我们首先考虑热噪声，结果显示，在局域化-去局域化跃迁点及附近，小系统的量子费舍尔信息呈现量子增强标度，但当系统尺寸超过特征 crossover 长度后，该优势消失；且 crossover 长度随温度升高而减小。随后我们考虑晶格隧穿强度的缺陷，发现了性质相似的 crossover：由超扩展标度表征的量子增强 regime，在系统尺寸足够大时让位于扩展标度——一种受经典限制的较弱形式。因此，不同的噪声机制对量子增强传感的可扩展性构成共同限制：将探针尺寸增大至超过依赖噪声的极限，会破坏计量学量子优势。
英文摘要
Localization-delocalization transitions have recently been proposed for building a class of efficient quantum many-body critical sensors. This work scrutinizes metrological performances of such devices by focusing on the Aubry-André-Harper model that supports a localization-delocalization transition at finite strength of the onsite potential. We identify a metrological quantum-to-classical crossover driven by the interplay between noise and system size, whereby quantum-enhanced scaling of the quantum Fisher information persists only up to a finite, noise-dependent characteristic system-size. We first consider thermal noise and show that, at and near the localization-delocalization transition, the quantum Fisher information exhibits quantum-enhanced scaling for small systems but the system is stripped of this advantage beyond the characteristic crossover length. The crossover length decreases with increasing temperature. We then consider imperfections in the lattice hopping strengths and find a qualitatively similar crossover. There, the quantum-enhanced regime, identified with super-extensive scaling, gives way to an extensive scaling-a classical-limited weaker form-at sufficiently large system sizes. Thus, distinct noise mechanisms lead to a common limitation on the scalability of quantum-enhanced sensing: increasing the probe size beyond a noise-dependent limit can destroy the metrological quantum advantage.
Comments11 pages, 5 figures
