Neural networks are becoming ubiquitous in various areas of physics as a successful machine learning(ML)technique for addressing different tasks.Based on ML technique,we propose and experimentally demonstrate an effic...Neural networks are becoming ubiquitous in various areas of physics as a successful machine learning(ML)technique for addressing different tasks.Based on ML technique,we propose and experimentally demonstrate an efficient method for state reconstruction of the widely used Sagnac polarization-entangled photon source.By properly modeling the target states,a multi-output fully connected neural network is well trained using only six of the sixteen measurement bases in standard tomography technique,and hence our method reduces the resource consumption without loss of accuracy.We demonstrate the ability of the neural network to predict state parameters with a high precision by using both simulated and experimental data.Explicitly,the mean absolute error for all the parameters is below 0.05 for the simulated data and a mean fidelity of 0.99 is achieved for experimentally generated states.Our method could be generalized to estimate other kinds of states,as well as other quantum information tasks.展开更多
We report the generation of polarization-entangled photon pairs in the 1550 nm band by pumping an uneven nonlinear interferometer loop with two orthogonally polarized counterpropagating pump pulses.The uneven nonlinea...We report the generation of polarization-entangled photon pairs in the 1550 nm band by pumping an uneven nonlinear interferometer loop with two orthogonally polarized counterpropagating pump pulses.The uneven nonlinear interferometer,providing a more ideal interference pattern due to the elimination of secondary maxima,consists of four pieces of dispersion-shifted fibers sandwiched with three pieces of standard single-mode fibers,and the lengths of the nonlinear fibers follow the binomial distribution.The mode number of the photon pairs deduced from the measured joint spectrum is∼1.03.The collection efficiency of the photon pairs is found to be∼94%(after background noise correction).The directly measured visibility of two-photon interference of the polarization-entangled photon pairs is∼92%,while no interference is observed in the direct detection of either the signal or idler photons.展开更多
We report an experimental generation of polarization-entangled photon pairs in a cold atomic ensemble. A single Stokes photon and one spin-wave excitation are simultaneously created via spontaneous Raman scattering. T...We report an experimental generation of polarization-entangled photon pairs in a cold atomic ensemble. A single Stokes photon and one spin-wave excitation are simultaneously created via spontaneous Raman scattering. The spin-wave excitation is then converted into an anti-Stokes photon via an electromagnetic-induced-transparency reading process. The measured cross-correlation functions between the Stokes and anti-Stokes photons for two orthogonal polarizations are -75 and 74, respectively, at a generation rate of the photon pair of -60/s. Based on such correlations, we obtain polarization-entangled photon pairs, whose Bell parameter is S = 2.77 4- 0.01, violating Bell-CHSH inequality by -77 standard deviations. The presented polarization-entangled photon source has high entanglement degree and fast generation rate, which will promise us to apply it in future quantum repeater.展开更多
Polarimeter is a vital precision tool used for measuring optical parameters through polarization variations.Among the wide range of application fields,the precise measurement of photosensitive materials is an unavoida...Polarimeter is a vital precision tool used for measuring optical parameters through polarization variations.Among the wide range of application fields,the precise measurement of photosensitive materials is an unavoidable task but faces immense obstacles due to the excessive input photons.Facing this situation,introducing a quantum source into the classical precision measurement system is a feasible way to enhance the detection accuracy under the low illumination regime.In this work,we employ polarization-entangled photon pairs in the classical polarimeter to precisely detect the relative phase retardance of uniform anisotropic media.The experimental results show that the accuracy can reach the nanometer scale at extremely low input intensity,and the stabilities are within 0.4%for all samples.Our work paves the way for polarization measurement at low incident light intensity,with potential applications in measuring photosensitive materials and remote monitoring scenarios.展开更多
基金Project supported by the National Key Research and Development Program of China (Grant No.2019YFA0705000)Leading-edge technology Program of Jiangsu Natural Science Foundation (Grant No.BK20192001)the National Natural Science Foundation of China (Grant No.11974178)。
文摘Neural networks are becoming ubiquitous in various areas of physics as a successful machine learning(ML)technique for addressing different tasks.Based on ML technique,we propose and experimentally demonstrate an efficient method for state reconstruction of the widely used Sagnac polarization-entangled photon source.By properly modeling the target states,a multi-output fully connected neural network is well trained using only six of the sixteen measurement bases in standard tomography technique,and hence our method reduces the resource consumption without loss of accuracy.We demonstrate the ability of the neural network to predict state parameters with a high precision by using both simulated and experimental data.Explicitly,the mean absolute error for all the parameters is below 0.05 for the simulated data and a mean fidelity of 0.99 is achieved for experimentally generated states.Our method could be generalized to estimate other kinds of states,as well as other quantum information tasks.
基金supported by the National Natural Science Foundation of China (Nos.12074283,91836302,11874279,and 62305240)
文摘We report the generation of polarization-entangled photon pairs in the 1550 nm band by pumping an uneven nonlinear interferometer loop with two orthogonally polarized counterpropagating pump pulses.The uneven nonlinear interferometer,providing a more ideal interference pattern due to the elimination of secondary maxima,consists of four pieces of dispersion-shifted fibers sandwiched with three pieces of standard single-mode fibers,and the lengths of the nonlinear fibers follow the binomial distribution.The mode number of the photon pairs deduced from the measured joint spectrum is∼1.03.The collection efficiency of the photon pairs is found to be∼94%(after background noise correction).The directly measured visibility of two-photon interference of the polarization-entangled photon pairs is∼92%,while no interference is observed in the direct detection of either the signal or idler photons.
基金the National Basic Research Program of China (2010CB923103)the National Natural Science Foundation of China (11475109, 11274211 and 60821004)
文摘We report an experimental generation of polarization-entangled photon pairs in a cold atomic ensemble. A single Stokes photon and one spin-wave excitation are simultaneously created via spontaneous Raman scattering. The spin-wave excitation is then converted into an anti-Stokes photon via an electromagnetic-induced-transparency reading process. The measured cross-correlation functions between the Stokes and anti-Stokes photons for two orthogonal polarizations are -75 and 74, respectively, at a generation rate of the photon pair of -60/s. Based on such correlations, we obtain polarization-entangled photon pairs, whose Bell parameter is S = 2.77 4- 0.01, violating Bell-CHSH inequality by -77 standard deviations. The presented polarization-entangled photon source has high entanglement degree and fast generation rate, which will promise us to apply it in future quantum repeater.
基金supported by the National Key Research and Development Program of China(Nos.2022YFB3903102 and 2022YFB3607700)the National Natural Science Foundation of China(No.62435018)+3 种基金the Innovation Program for Quantum Science and Technology(No.2021ZD0301100)the USTC Research Funds of the Double First-Class Initiative(No.YD2030002023)the Research Cooperation Fund of SAST,CASC(No.SAST2022-075)the Postdoctoral Fellowship Program of CPSF(No.GZC20232559)。
文摘Polarimeter is a vital precision tool used for measuring optical parameters through polarization variations.Among the wide range of application fields,the precise measurement of photosensitive materials is an unavoidable task but faces immense obstacles due to the excessive input photons.Facing this situation,introducing a quantum source into the classical precision measurement system is a feasible way to enhance the detection accuracy under the low illumination regime.In this work,we employ polarization-entangled photon pairs in the classical polarimeter to precisely detect the relative phase retardance of uniform anisotropic media.The experimental results show that the accuracy can reach the nanometer scale at extremely low input intensity,and the stabilities are within 0.4%for all samples.Our work paves the way for polarization measurement at low incident light intensity,with potential applications in measuring photosensitive materials and remote monitoring scenarios.
