Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted ...Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted into phase signals,it is interesting and important to consider measuring small longitudinal phase shifts by using weak measurement.Here,we propose and experimentally demonstrate a novel weak measurement amplification-based small longitudinal phase estimation,which is suitable for polarization interferometry.We realize one order of magnitude amplification measurement of a small phase signal directly introduced by a liquid crystal variable retarder and show that it is robust to the imperfection of interference.Besides,we analyze the effect of magnification error which is never considered in the previous works,and find the constraint on the magnification.Our results may find important applications in high-precision measurements,e.g.,gravitational wave detection.展开更多
Quantum coherence is the most distinct feature of quantum mechanics.However,inevitable decoherence processes will finally destroy it and make the"Schrödinger's cat"invisible in our classical world.I...Quantum coherence is the most distinct feature of quantum mechanics.However,inevitable decoherence processes will finally destroy it and make the"Schrödinger's cat"invisible in our classical world.In this"quantum-to-classical transition",the so-called"largeness"plays a critical role.We experimentally study the largeness phenomena in the bipartite entanglement decay process through a depolarizing channel with two-photon entangled states generated from a spontaneous parametric down-conversion source.Our experiment demonstrates how the speed of entanglement decay and the time when"entanglement sudden death"happens depend on the size of the system exposed to the environment noise.展开更多
We present a theoretical and experimental study on the bandwidth of parametric down-converted photons generated from periodically poled lithium niobate(PPLN)crystal pumped by a pulsed laser.By comparison of crystals w...We present a theoretical and experimental study on the bandwidth of parametric down-converted photons generated from periodically poled lithium niobate(PPLN)crystal pumped by a pulsed laser.By comparison of crystals with different lengths and pump beams of different bandwidths,we demonstrate that the bandwidth of down-converted photons will increase for a broader bandwidth of pump pulse and decrease for a longer crystal,but the influence of crystal length will become weaker along with increase of both crystal length and pump pulse bandwidth.Especially under the conditions of our experiment,the bandwidth almost remains unchanged for longer crystals when pumped by a femtosecond laser.This may be helpful for schemes in which pulsed lasers are used to pump PPLN crystals.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 92065113, 11904357, 62075208, and 12174367)the Innovation Programme for Quantum Science and Technology (Grant No. 2021ZD0301604)+1 种基金the National Key Research and Development Program of China (Grant No. 2021YFE0113100)supported by Beijing Academy of Quantum Information Sciences
文摘Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted into phase signals,it is interesting and important to consider measuring small longitudinal phase shifts by using weak measurement.Here,we propose and experimentally demonstrate a novel weak measurement amplification-based small longitudinal phase estimation,which is suitable for polarization interferometry.We realize one order of magnitude amplification measurement of a small phase signal directly introduced by a liquid crystal variable retarder and show that it is robust to the imperfection of interference.Besides,we analyze the effect of magnification error which is never considered in the previous works,and find the constraint on the magnification.Our results may find important applications in high-precision measurements,e.g.,gravitational wave detection.
基金supported by the Innovation Program for Quantum Science and Technology (2021ZD0301400)the National Natural Science Foundation of China (61725504, 11774335, 11821404, U19A2075)+1 种基金the Fundamental Research Funds for the Central Universities ( WK2030380017, WK2030000056)Anhui Initiative in Quantum Information Technologies (AHY020100, AHY060300)
基金Supported by the National Basic Research Program under Grant No 2006CB921907, the National Natural Science Foundation of China under Grant Nos 10774139 and 60621064, Knowledge Innovation Project of Chinese Academy of Sciences, the Program for New Century Excellent Talents in University, International Cooperation Program of Chinese Academy of Sciences, and Ministry of Science and Technology of China, the Foundation for Author of National Excellent Doctoral Dissertation of China under Grant 200729, and China Postdoctoral Science Foundation under Grant No 20070420736.
基金by the National Basic Research Program of China under Grant No 2011CB921200the National Natural Science Foundation of China under Grant Nos 11074242 and 10874162+3 种基金the Knowledge Innovation Project of Chinese Academy of Sciencesthe Program for New Century Excellent Talents in Universitythe International Cooperation Program from CAS and the Ministry of Science and Technology of Chinathe Foundation for the Author of National Excellent Doctoral Dissertation of of China under Grant No 200729.
文摘Quantum coherence is the most distinct feature of quantum mechanics.However,inevitable decoherence processes will finally destroy it and make the"Schrödinger's cat"invisible in our classical world.In this"quantum-to-classical transition",the so-called"largeness"plays a critical role.We experimentally study the largeness phenomena in the bipartite entanglement decay process through a depolarizing channel with two-photon entangled states generated from a spontaneous parametric down-conversion source.Our experiment demonstrates how the speed of entanglement decay and the time when"entanglement sudden death"happens depend on the size of the system exposed to the environment noise.
基金by the National Basic Research Program of China under Grant No 2006CB921907the National Natural Science Foundation of China under Grant No 10774139+3 种基金the Innovation Funds from Chinese Academy of Sciencesthe Program for New Century Excellent Talents in Universitythe Foundation for Author of National Excellent Doctoral Dissertation of China under Grant No 200729the Fundamental Research Funds for the Central Universities.
文摘We present a theoretical and experimental study on the bandwidth of parametric down-converted photons generated from periodically poled lithium niobate(PPLN)crystal pumped by a pulsed laser.By comparison of crystals with different lengths and pump beams of different bandwidths,we demonstrate that the bandwidth of down-converted photons will increase for a broader bandwidth of pump pulse and decrease for a longer crystal,but the influence of crystal length will become weaker along with increase of both crystal length and pump pulse bandwidth.Especially under the conditions of our experiment,the bandwidth almost remains unchanged for longer crystals when pumped by a femtosecond laser.This may be helpful for schemes in which pulsed lasers are used to pump PPLN crystals.
基金supported by the National Key Research and Development Program of China(2021YFE0113100 and 2017YFA0304100)the National Natural Science Foundation of China(11774335,11734015,11874345,11821404,11904357,11974189,12174367,and 12175106)+4 种基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS,QYZDYSSW-SLH003)Science Foundation of the CAS(ZDRW-XH-2019-1)the Fundamental Research Funds for the Central UniversitiesUSTC Tang ScholarshipScience and Technological Fund of Anhui Province for Outstanding Youth(2008085J02)。
基金supported by the National Natural Science Foundation of China(6132790161490711+7 种基金11274289113254196122502511474268and 11374288)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(XDB01030300)the National Youth Top Talent Support Program of National High-level Personnel of Special Support Programthe Fundamental Research Funds for the Central Universities(WK2470000018)
