Stably Trapping Of Ions On A Chip Trap

In recent 20 years,quantum information technologies have been developed rapidly,quantum computing which is one of the most important branch gets high attention of the whole world.There are many candidates for achieving quantum computer,and ion trap benefiting by some advantages such like long coherence time of qubit and easiness of controlling,is regarded as one of the most promising scheme.Early ion trap is made of big electrodes,and ions are trapped in it,this kind of trap makes it difficult to accomplish qubits expanding in large scale,so it develops into easily scalable chip trap.This chip trap,by nanofabrication technologies,fabricates electrodes onto a semiconductor or insulator substrate,and through applying different voltage distributions on the electrodes,it realizes trapping ions and classical controlling.However,ions in chip trap are very close to the electrodes,and ions there are very sensitive to the trap structure,the voltages applied on the electrodes and other parameters.Hence,designing structure of chip trap,optimizing parameters of the trap and accurately designing voltages distribution on electrodes are great important for stably trapping ions,and these have been key research issues of ion quantum computing.The second chapter of this thesis expounds ion trapping theory on a chip trap,analyzes the way of generating spatial potential above a rectangular plat electrode,introduces the method of construction trapping potential and brings out the procedure of calculating voltage distributions of the electrodes for generating trapping potential,at last,applications of this procedure in ion trapping experiment are discussed.There is the standard procedure to simulate spatial structures of trapped ion crystals,the third points out two defects of the standard procedure: inescapability of solving partial derivative and inaccuracy of solutions.Thus a new method of calculating stable structure of ion crystals based on Simulated Annealing algorithm is introduced,and simulations are made in both harmonic potential and anharmonic potential in one dimension.By comparing the results of these two methods,viability and superiority of new method are both verified.Then an idea of studying influences on stably trapping from noises is mentionedThe fourth part briefly introduces experiment equipments and experiment procedure in ion trapping,and results of successfully trapping an ion directed by theories analyses above is shown.