Accurately estimating the overlap between quantum states is a fundamental task in quantum information processing.While various strategies using distinct quantum measurements have been proposed for overlap estimation,t...Accurately estimating the overlap between quantum states is a fundamental task in quantum information processing.While various strategies using distinct quantum measurements have been proposed for overlap estimation,the lack of experimental benchmarks on estimation precision limits strategy selection in different situations.Here we compare the performance of four practical strategies for overlap estimation,including tomography-tomography,tomographyprojection,Schur collective measurement and optical swap test using photonic quantum systems.We encode the quantum states on the polarization and path degrees of freedom of single photons.The corresponding measurements are performed by photon detection on certain modes following single-photon mode transformation or two-photon interference.We further propose an adaptive strategy with optimized precision in full-range overlap estimation.Our results shed new light on extracting the parameter of interest from quantum systems,prompting the design of efficientquantum protocols.展开更多
Identifying optical modes in chaotic cavities is crucial for exploring and understanding the physical mechanisms inside them.Compared with free spectral range estimation,the direct imaging technique has the capability...Identifying optical modes in chaotic cavities is crucial for exploring and understanding the physical mechanisms inside them.Compared with free spectral range estimation,the direct imaging technique has the capability of providing more precise mode information,but it is extremely time-consuming and susceptible to environmental perturbations.Here we report a high-speed imaging technique for visualizing field distributions in chaotic microcavities.When a silicon microdisk is excited by a femtosecond laser,free carriers are locally generated,thereby reducing the refractive index.Under a constant laser power,the spatial distribution of mode inside the silicon microdisk is proportional to its wavelength shift and can be precisely identified by comparing it with numerical simulation.With the assistance of a galvanometer,imaging a mode profile only takes a few hundred milliseconds to a few seconds,orders of magnitude faster than previous reports.The impacts of slight fabrication deviations on spectra have also been identified.展开更多
基金supported by National Natural Science Foundation of China(GrantsNo.U24A2017,No.12347104 and No.12461160276)the National Key Researchand Development Program of China(Grants No.2023YFC2205802)+1 种基金Natural Science Foundation of Jiangsu Province(Grants No.BK20243060 and No.BK20233001)in part by State Key Laboratory of Advanced Optical Communication Systems and Networks,China.
文摘Accurately estimating the overlap between quantum states is a fundamental task in quantum information processing.While various strategies using distinct quantum measurements have been proposed for overlap estimation,the lack of experimental benchmarks on estimation precision limits strategy selection in different situations.Here we compare the performance of four practical strategies for overlap estimation,including tomography-tomography,tomographyprojection,Schur collective measurement and optical swap test using photonic quantum systems.We encode the quantum states on the polarization and path degrees of freedom of single photons.The corresponding measurements are performed by photon detection on certain modes following single-photon mode transformation or two-photon interference.We further propose an adaptive strategy with optimized precision in full-range overlap estimation.Our results shed new light on extracting the parameter of interest from quantum systems,prompting the design of efficientquantum protocols.
基金National Key Research and Development Program of China(2024YFB2809200)National Natural Science Foundation of China(12334016,12025402,62125501,62335005,12261131500,92250302)+2 种基金New Cornerstone Science Foundation(Xplorer Prize)Shenzhen Fundamental Research Projects(JCYJ20241202123719025,JCYJ20241202123729038)Fundamental Research Funds for the Central Universities(2022FRFK01013)。
文摘Identifying optical modes in chaotic cavities is crucial for exploring and understanding the physical mechanisms inside them.Compared with free spectral range estimation,the direct imaging technique has the capability of providing more precise mode information,but it is extremely time-consuming and susceptible to environmental perturbations.Here we report a high-speed imaging technique for visualizing field distributions in chaotic microcavities.When a silicon microdisk is excited by a femtosecond laser,free carriers are locally generated,thereby reducing the refractive index.Under a constant laser power,the spatial distribution of mode inside the silicon microdisk is proportional to its wavelength shift and can be precisely identified by comparing it with numerical simulation.With the assistance of a galvanometer,imaging a mode profile only takes a few hundred milliseconds to a few seconds,orders of magnitude faster than previous reports.The impacts of slight fabrication deviations on spectra have also been identified.
