Experimental Adiabatic Quantum Control On Single Spin System In Solids

Quantum control is one of the most important research areas in modern physics.The fundamental problem in the field is how to adjust the parameters,which control the evolution of the quantum system,to reach the desired final state.In recent years,great progress has been made both in theoretical and experimental research for quantum control.Regarding its applications,quantum control is an important tool in many fields,such as the construction of quantum gates in quantum computing,control of chemical reactions at the molecular or atomic level and the control of molecular machines in nanoscience.Adiabatic quantum control is a good choice when the target state is the eigenstate of the quantum system.As according to the quantum adiabatic theorem,if the initial state is one of the system eigenstates and the parameters that control the evolution vary slowly,the system will remain on this eigenstate.The application of adiabatic quantum control in the field of quantum computation is the so-called adiabatic quantum computation.However,any real quantum system is not completely isolated,and the existence of noise will significantly reduce the fidelity of the control.Now the challenge lies at how to realize high fidelity adiabatic control and further implementation of its application of the quantum system in a realistic noisy environment.In this thesis,we utilize the nitrogen-vacancy(NV)center in diamond as a single quantum system to study its evolution under specific control schemes.Here we introduce the experimental research we have done concerning the adiabatic quantum control of a solid state single quantum system based on our home-built optically detected magnetic resonance platform.The main content is listed as the following three work:1.We have realized adiabatic quantum algorithms based on a single spin sys-tem in diamond at room temperature.We demonstrated the whole process of quantum factorization,taking 35 as an example.In order to overcome the decoherence effect caused by the system noise,we have developed a new optimal control technique,which for the first time applied on the nuclear and electronic spin simultaneously.We realized high fidelity quantum control on the electronic-nuclear spin hybrid system.2.Adiabatic quantum control plays an important role in many fields besides quantum computation and the starting point of which is to ensure the evo-lution process is truly adiabatic.For a deeper understanding of adiabatic quantum evolution,we experimentally tested a newly proposed adiabatic condition.It shows that even with vanishing energy gaps adiabatic evolu-tion can still be achieved,which beyond the scope of traditional adiabatic theorem.3.We designed a new adiabatic protocol based on the new condition,the merit of which is nearly unit fidelity can be reached within finite evolution time.This so-called pulsed adiabatic protocol provides a new possibility for high fidelity quantum control.