物理学报2025，Vol.74Issue(10)：20-27,8.DOI:10.7498/aps.74.20241781
两个自旋-1/2原子的自旋交换
Spin exchange of two spin-1/2 atoms
摘要
Abstract
The quantum Cheshire cat effect is an important phenomenon in quantum mechanics that reveals the separability of physical properties from their carriers.This effect transcends the classical framework whose attributes must be inherently attached to objects,providing new perspectives for quantum information and precision measurement.According to the quantum Cheshire cat effect,we prepare a pre-selected state of a spin-1/2 atomic system composed of two particles through a pre-selection process.We conduct quantum weak measurements on the spins and positions of these two atoms and extract weak values by using the method of imaginary time evolution(ITE).Subsequently,we perform post-selection on these two atoms and design two distinct post-selected states.Initially,we calculate analytical solutions when both atoms encounter these two different post-selected states separately.Then,during the stage of obtaining weak values via ITE,we first discuss the scenario with only one post-selected state.In this case,our experimental goal is to achieve spin exchange between the two atoms.We use ITE to obtain normalized coincidence rate for the system.By linearly fitting these normalized coincidence rate,we derive numerical solutions for the weak values of the system.The comparison between the analytical solutions and numerical results indicates that they are in close agreement,demonstrating that our method promotes spin exchange between the two atoms.Next,we examine scenarios involving both post-selected states in the post-selection process.After completing weak measurements on particles,delayed-choice allows them to evolve along different paths ultimately leading to distinct post-selected states.One particular post-selected state that results in final measurement outcomes indicates that the spin exchange occurs between both particles with amplification.Conversely,the other post-selected state ensures that even after undergoing weak measurement and delayed-choice,the states of the two particles remain consistent with their pre-measurement conditions.We also compare the analytical and numerical solutions of the experiment involving delayed choice and find that they are very consistent with each other.This consistency indicates that delayed-choice indeed has a significant influence on whether the final exchange occurs.Our research theoretically confirms the feasibility of fermionic systems within bipartite quantum Cheshire cat effects and illustrates how delayed-choice influences quantum Cheshire cat effects in spin-1/2 atomic systems.关键词
量子信息/弱值/量子柴郡猫Key words
quantum information/weak value/quantum Cheshire cat引用本文复制引用
潘泽明,谭乃铭,高超,姚治海,王晓茜..两个自旋-1/2原子的自旋交换[J].物理学报,2025,74(10):20-27,8.基金项目
吉林省基础研究计划基金(批准号:YDZJ202101ZYTS030)资助的课题. Project supported by the Jilin Provincial Research Foundation for Basic Research,China(Grant No.YDZJ202101ZYTS030). （批准号:YDZJ202101ZYTS030）
