Yadin Benjamin, Fadel Matteo, Gessner Manuel
School of Mathematical Sciences and Centre for the Mathematics and Theoretical Physics of Quantum Non-Equilibrium Systems, University of Nottingham, Nottingham, UK.
Wolfson College, University of Oxford, Oxford, UK.
Nat Commun. 2021 Apr 23;12(1):2410. doi: 10.1038/s41467-021-22353-3.
The Einstein-Podolsky-Rosen (EPR) paradox plays a fundamental role in our understanding of quantum mechanics, and is associated with the possibility of predicting the results of non-commuting measurements with a precision that seems to violate the uncertainty principle. This apparent contradiction to complementarity is made possible by nonclassical correlations stronger than entanglement, called steering. Quantum information recognises steering as an essential resource for a number of tasks but, contrary to entanglement, its role for metrology has so far remained unclear. Here, we formulate the EPR paradox in the framework of quantum metrology, showing that it enables the precise estimation of a local phase shift and of its generating observable. Employing a stricter formulation of quantum complementarity, we derive a criterion based on the quantum Fisher information that detects steering in a larger class of states than well-known uncertainty-based criteria. Our result identifies useful steering for quantum-enhanced precision measurements and allows one to uncover steering of non-Gaussian states in state-of-the-art experiments.
爱因斯坦 - 波多尔斯基 - 罗森（EPR）悖论在我们对量子力学的理解中起着基础性作用，并且与以似乎违反不确定性原理的精度预测非对易测量结果的可能性相关联。这种与互补性的明显矛盾是由比纠缠更强的非经典关联——称为导引实现的。量子信息将导引视为许多任务的基本资源，但与纠缠不同，其在计量学中的作用迄今仍不明确。在此，我们在量子计量学框架内阐述EPR悖论，表明它能够精确估计局部相移及其生成可观测量。通过采用更严格的量子互补性表述，我们基于量子费希尔信息推导出一个判据，该判据能在比著名的基于不确定性的判据更大的一类态中检测到导引。我们的结果确定了对量子增强精度测量有用的导引，并允许人们在当前最先进的实验中揭示非高斯态的导引。
