| plied in many frontier fields.Greenberger-Horne-Zeilinger(GHZ)state and W state are two kinds of typical three-dimensional entangled states.Researchers have used a number of systems to prepare these two kinds of entangled states,in which the circuit quantum electrodynamics(QED)system has become the most potential.Because the superconducting quantum bits(SQs)of the circuit QED system are potentially adaptable to integrated devices in quantum computing and can be controlled by adjusting the electromagnetic signal and energy structures.On the other hand,the adiabatic process is a typical technique of preparing entangled states.However,the adiabatic process technique requires long evolution time in order to satisfy the adia batic approximation condition.Therefore,a new kind of technique called adiabatic shortcut has attracted intensive concern for the reason that it can accelerate the adiabatic process.This thesis proposes two theoretical schemes for fast generating GHZ state and W state of three superconducting qubits via superadiabatic-based shortcut and a chosen path shortcut,respectively.The main contents of the thesis are as follows(1)We propose a theoretical scheme for fast generating GHZ state of three su-perconducting qubits via superadiabatic-based shortcut.Firstly,with the help of quantum Zeno dynamics,we obtain the effective Hamiltonian of the system,then we choose a suitable counterdiabatic Hamiltonian in the same form as the effective Hamiltonian and add it to the effective Hamiltonian in order to construct adiabatic shortcut,which can make the system evolve along one of the superadiabatic eigen-states and thus accelerate the evolution process of the system.More importantly,the superadiabatic scheme does not need an additional coupling between the initial and finial state,which ensures its high experimental feasibility.In addition,numer-ical simulation results show that the proposed scheme is robust against the cavity photon leakage,spontaneous emission and the dephasing of SQs.(2)We present a scheme of choosing a dressed state as an evolutive path to prepare three-superconducting qubit W state.In the circuit QED system,there are three superconducting qubits trapped respectively in three coplanar waveguide res-onators(CPWRs),which are coupled to a superconducting coupler(SCC)qubit With the help of quantum Zeno dynamics,we get the effective Hamiltonian of the system.Our strategy is adding two auxiliary pulses to the effective Hamiltonian New driving pulses can cancel nonadiabatic transitions,so the whole system will evolve exactly along the chosen path.By setting boundary conditions,the W s-tate can be obtained in a short time.Furthermore,in the chosen evolutive-path state,the intermediate state’s population can be restricted by setting appropriate parameters,which is very useful for resisting the effects of decoherence.Numerical simulations indicate that the proposed scheme is robust against the cavity photon leakage,spontaneous emissions,dephasing of SQs and the parameter fluctuationsThe schemes in this thesis are proposed under the consideration of experimental conditions,which ensure the schemes have higher certainty.More importantly,the above schemes are of great value for the study of adiabatic shortcut technology and preparing three-dimensional entanglement state and will be useful for the develop-ment of quantum computation and quantum communication. |
