期刊
PHYSICAL REVIEW RESEARCH
卷 3, 期 4, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevResearch.3.043122
关键词
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The study demonstrates an experimental method using randomized measurements to extract the quantum Fisher information and successfully applies it to a 4-qubit state. The results show that this method has advantages in estimating QFI and multipartite entanglement, and is applicable to different quantum platforms.
The quantum Fisher information (QFI) represents a fundamental concept in quantum physics. It quantifies the metrological potential of quantum states in quantum parameter estimation measurements, and is intrinsically related to quantum geometry and multipartite entanglement of many-body systems. Using a nitrogen-vacancy center spin in diamond, we experimentally demonstrate a randomized-measurement method to extract the QFI of the qubit, for both pure and mixed states. We then apply this scheme to a 4-qubit state, using a superconducting quantum computer, and show that it provides access to the sub-QFI, which sets a lower bound on the QFI for general mixed states. We numerically study the scaling of statistical error, considering N-qubit states, to illustrate the advantage of our randomized-measurement approach in estimating the QFI and multipartite entanglement. Our results highlight the general applicability of our method to different quantum platforms, including solid-state spin systems, superconducting quantum computers, and trapped ions.
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