Experimental Studies On One-dimensional Far-detuned Optical Lattice

With the development of modern science and technology,quantum communication has received extensive attention because of its high efficiency of information transmission and high security.But the loss of the optical fiber and the atmosphere causes the information to be spread far and long.The scientists put forward the concept of quantum memory and the transmission distance segment to achieve a quantum secure communication relay transmission,so as to break through the communication distance limit.The scheme puts forward a very high request to the storage time and the reading efficiency of the quantum memory.In recent years,the research progress of quantum memory at home and abroad can be seen,although there have been some progress in quantum storage technology,but most of them are limited by a short storage time.And in the process of improving the storage time,in which the optical lattice of the program has been favored by the experimental group.Early in 1968,Russian scientists Letokhov pointed out that we can use light on atom mechanical force to trap neutral atoms,and first proposed to trap cold atom by standing wave field.In 1992,Verkevk and Jessen,realized the one-dimensional optical lattice in experiment for the first time,and studied the dynamic behavior of cold atoms in one-dimensional optical lattices,classical motion and magnetic properties.Subsequently,Hemmerich and Grynberg realized the two-dimensional optical lattices and 3D optical lattice,and researched the cold atom quantized motion.Compared with the periodic lattice potential field in the presence of lattice defects,the problem of thermal noise and lattice defects in the cold atomic system in the optical lattice periodic potential field was solved.Our experimental team select the 87 Rb cold atomic ensemble to set up an experimental system,and the goal is to achieve over 16 s of the quantum information storage.The main work of this paper is to complete the optimization of the optical path of the magneto optical trap,build the polarization gradient cooling optical path,and analyze the characteristics of the multimode 1064 nm fiber laser.We have built a cycle of 25?m one-dimensional far detuned optical lattice potential field,and have loaded the cold rubidium atoms in an optical lattice.Research work and achievements are as follows:The first part,The recovery of the experimental optical path is accomplished,and the collimation and beam splitting of the six beam of the magneto optical trap are optimized.We also have optimized the magnetic optical trap,so that the light field and the magnetic field center are strictly consistent to ensure the maximum number of atoms and improve the stability of the atomic number.The second part,We redesigned the cooling light path for the completion of the cooling MOT and polarization gradient cooling process.The characteristics of multimode 1064 nm fiber laser are analyzed.The optical lattice potential field and the perfect imaging optical path are designed and built.The third part,Using Labview program and timing card to control the opening and closing of the instrument in each experiment stage,observing the one-dimensional optical lattice,and measuring the temperature,density and optical trap lifetime of the cold atoms in the optical trap.