Quantum Computation Based On Non-decoherence Subspace

Quantum computition,as a new hot technology in the 21st century,its computing speed and power are obviously more superior to classical computition.However,the sys-tem needs to maintain stable coherence in the process of processing quantum information,which will be destroyed due to the inevitable interaction between quantum system and en-vironment.Therefore,how to create a non-decoherent subspace to overcome the influence of decoherence has become one of the.keys to build a quantum computer.This paper mainly studied two kinds of non-decoherence subspace:adiabatic sub-space and zeno subspace.Firstly,we introduce holonomic quantum computation based on the adiabatic theory.After a cycle of adiabatic evolution,quantum system will get a phase,which only depends on the evolution path and has nothing to do with the speed of e volution.Besides,the geometric phase can be abel or non-abel,depending on the energy degeneracy.Although the geometric phase can eliminate the influence on the control of the system,the adiabatic evolution process is very slow,which will increase the probability of spontaneous emission or decoherence.In order to eliminate this shortcoming,we will firstly study zeno dynamics by using continuous projection measurement,and then summary three methods of obtaining zeno subspace.We also show the equivalence between adiabatic evolution and zeno dynamics,which means that whenever a holonomic quantum computation is ob-tained by adiabatic evolution,we can always achieve it by zeno dynamics correspondingly.Finally,we use zeno dynamics to design some schemes to realize quantum gate,which provides a new way to realize universal quantum computer.In addition,we introduce the electromagnetic duality theorem of geometric phase in chapter 3,and find that the A-C effect is the electromagnetic duality of HMW effect un-der two four-vector potential formulation,and in the process of combing the knowledge of quantum zeno dynamics in chapter 4,to a certain extent,we show the mathematics,as a tool,plays an important role in in the study of physics,and their relationship is pretty subtle!...