期刊
PHYSICAL REVIEW LETTERS
卷 125, 期 3, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevLett.125.030506
关键词
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资金
- National Key Research and Development Program of China [2016YFA0302700, 2017YFA0304100]
- National Natural Science Foundation of China [11874344, 11704371, 61835004, 61327901, 11774335, 91536219, 11821404]
- Key Research Program of Frontier Sciences, CAS [QYZDY-SSW-SLH003]
- Anhui Initiative in Quantum Information Technologies [AHY020100, AHY060300]
- Fundamental Research Funds for the Central Universities [WK2030020019, WK2470000026]
- Science Foundation of the CAS [ZDRW-XH-2019-1]
The initialization of a quantum system into a certain state is a crucial aspect of quantum information science. While a variety of measurement strategies have been developed to characterize how well the system is initialized, for a given one, there is in general a trade-off between its efficiency and the accessible information of the quantum state. Conventional quantum state tomography can characterize unknown states while requiring exponentially expensive time-consuming postprocessing. Alternatively, recent theoretical breakthroughs show that quantum state verification provides a technique to quantify the prepared state with significantly fewer samples, especially for multipartite entangled states. In this Letter, we modify the original proposal to be robust to practical imperfections, and experimentally implement a scalable quantum state verification on two-qubit and four-qubit entangled states with nonadaptive local measurements. For all the tested states, the estimated infidelity is inversely proportional to the number of samples, which illustrates the power to characterize a quantum state with a small number of samples. Compared to the globally optimal strategy which requires nonlocal measurements, the efficiency in our experiment is only worse by a small constant factor (<2.5). We compare the performance difference between quantum state verification and quantum state tomography in an experiment to characterize a four-photon GreenbergerHorne-Zeilinger state, and the results indicate the advantage of quantum state verification in both the achieved efficiency and precision.
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