Induction And Measurement Of Spin Currents In Spinor Bose-Einstein Condensate

Bose-Einstein condensates(BECs)provide a pure platform for studying nonlinear physics,atomic optics,quantum simulation and quantum information,and are an excellent and controllable macroscopic quantum system.Spin currents have wide applications in solid-state systems,and using neutral atomic gas BECs to simulate spin currents and investigate related phenomena in spintronics is of great importance for spin-based quantum computing and other technological applications.Based on this,this thesis uses a fully optical experimental method to prepare Na spin BECs,and successfully induces spin currents by a gradient magnetic field.The dynamic characteristics of different spin components under magnetic forces were studied.This provides a basis for generating longer spin coherence and improving the sensitivity of spin mixture interference measurements in spinor BECs.This thesis first introduces the research progress and theoretical basis of BECs,and highlights the core role of spin currents in exploring related theories in spintronics.The specific steps for preparing BECs are detailed,including laser cooling,loading in magnetic-optical traps,compressing magnetic-optical traps,polarization gradient cooling,and evaporative cooling.The experimental system for achieving BECs is described,including the laser system and vacuum system.Using a magnetic field gradient to induce spin currents,the relative positions of different m _F components were recorded to study the spin currents generated.Three spin components were recorded for their positions under varying hold times and maximum distances traveled under different magnetic field gradients.The experimental results show that the position z for spin m _F=0 does not change with the magnetic field.The spin current generated by other components will gradually increase as the induced magnetic field strength increases.This thesis consists of five chapters:Chapter 1 explains the background of BEC research,Chapter 2 introduces the theoretical methods for achieving Na atomic BECs,Chapter 3 describes how to achieve Na BECs experimentally,Chapter 4 discusses how to induce spin currents in spinor BECs using a gradient magnetic field,and Chapter 5 provides a summary and outlook.