In optical metrological protocols to measure physical quantities,it is,in principle,always beneficial to in crease photon number n to improve measurement precision.However,practical constraints prevent the arbitrary i...In optical metrological protocols to measure physical quantities,it is,in principle,always beneficial to in crease photon number n to improve measurement precision.However,practical constraints prevent the arbitrary increase of n due to the imperfections of a practical detector,especially when the detector response is dominated by the saturation effect.In this work,we show that a modified weak measurement protocol,namely,biased weak measurement significantly improves the precision of optical metrology in the presence of saturation effect.This method detects an ultra-small fraction of photons while main tains a considerable amount of metrological information.The biased pre-coupling leads to an additi onal reduction of photons in the post-selection and gene rates an extinction point in the spectrum distribution,which is extremely sensitive to the estimated parameter and difficult to be saturated.Therefore,the Fisher information can be persistently enhanced by increasing the photon number.In our magnetic-sensing experiment,biased weak measurement achieves precision approximately one order of magnitude better than those of previously used methods.The proposed method can be applied in various optical measurement schemes to remarkably mitigate the detector saturation effect with low-cost apparatuses.展开更多
基金the National Key Research and Development Program of China(Nos.2017YFA0304100,2016YFA0302700)National Natural Science Foundation of China(Grant Nos.11874344,92065107,61835004,11774335,91536219,11821404)+3 种基金Key Research Program of Frontier Sciences,CAS(No.QYZDY-SSW-SLH003)Anhui Initiative in Quantum Information Technologies(AHY020100,AHY060300)the Fundamental Research Funds for the Central Universities(Grant Nos.WK2030020019,WK2470000026)Science Foundation of the CAS(No.ZDRW-XH-2019-1).
文摘In optical metrological protocols to measure physical quantities,it is,in principle,always beneficial to in crease photon number n to improve measurement precision.However,practical constraints prevent the arbitrary increase of n due to the imperfections of a practical detector,especially when the detector response is dominated by the saturation effect.In this work,we show that a modified weak measurement protocol,namely,biased weak measurement significantly improves the precision of optical metrology in the presence of saturation effect.This method detects an ultra-small fraction of photons while main tains a considerable amount of metrological information.The biased pre-coupling leads to an additi onal reduction of photons in the post-selection and gene rates an extinction point in the spectrum distribution,which is extremely sensitive to the estimated parameter and difficult to be saturated.Therefore,the Fisher information can be persistently enhanced by increasing the photon number.In our magnetic-sensing experiment,biased weak measurement achieves precision approximately one order of magnitude better than those of previously used methods.The proposed method can be applied in various optical measurement schemes to remarkably mitigate the detector saturation effect with low-cost apparatuses.
