Experimental Study Of Quantum Entanglement In Optical Lattices

The objective of this dissertation is to study the realization and detection of manybody spin entanglement in optical lattice.A large amount of entangled qubits is one of the key foundations of quantum computation,since the experimental platform of optical lattice was limited by the imaging resolution and weak ability of single qubit manipulation for a long time,its application on quantum computation rarely got attention.Recently,due to the development of high-resolution imaging,the imaging of single atom in optical lattices was realized,and the controllability of single atom in optical lattice is improved significantly.Furthermore,as Mott Insulator phase with unit filling in optical lattices contains a huge amount of atoms,quntum computation platform based on optical lattices could have a high scalability.Through the following steps:cooling in three dimensional magnetic-optical trap,evaporative cooling in magnetic trap,optical transfer and evaporative cooling in dipole trap,we achieved Rb87 Bose-Einstein Condensation first.Subsequently,we loaded them into one-dimensional optical lattice to get several layers of atoms.With positiondependent Zeeman energy split generated by magnetic gradient,we chose single layer of atoms with microwave flip and removed the atoms in other layers with resonant laser.The evaporation in a hybrid trap which is consisted of a dimple trap and a magnetic trap further decreased the atoms temperature and atoms number,providing a good initial condition for the creation of Mott Insulator phase.Finally we realized the phase transition from superfluid to Mott Insulator by adiabatically ramping up the depth of two dimensional optical lattice.With high-resolution imaging,we confirmed that the filling of Mott Insulator is close to 1,which provides the material basis for spin-entanglement experiment.The realization of spin-entanglement needs the ability to control different spin components,so we designed and employed spin-dependent superlattice in our setup.Moreover,we confirmed the spin-dependent effect with microwave spectrum and observed the superexchange process in double wells experimentally.Based on these results,we designed and simulated theoretically a scheme to generate one-dimensional spin-entangled chain with(?)gate operation and verify the entanglement in experiment.Through these works,we built a optical-lattices experimental platform with excellent ability to control and detect single atom,which lays a solid foundation for the broader experimental research on quantum information and quantum physics.