Digital Quantum Simulation On Superconducting Qubits

Superconducting quantum system,as one of the most promising systems to realize universal quantum computer,has always been viewed as a hot field by researchers at home and abroad.In general,there are two main research directions in this field.One focuses on hardware research,which can promote the realization of fault tolerant universal quantum computing by expanding the number of integrated qubits on chips,promoting the quality of qubits and improving the control accuracy.Others focus on the application of quantum computer,and try to demonstrate the exponential growth advantage of quantum computer compared with classical computer through various quantum algorithms and quantum simulation experiments,so as to illustrate its broad application prospects.I have been learning the basic theories and experimental techniques of superconducting quantum computing since I entered the graduate school,and have designed and completed several experiments related to quantum simulation on this basis.The first chapter introduces the basic knowledge of quantum computing,including the concept of qubit,manipulation and measurement of qubit,as well as qubit decoherence.Then I introduce several requirements to realize quantum computation in reality.In addition,two kinds of quantum simulation methods,analog quantum simulation and digital quantum simulation,are introduced.From chapter 2,I begin to focus on the superconducting quantum computing system.Starting from the LC oscillation circuit,I introduce its quantization process,and then a nonlinear element——Josephson junction is introduced to get nonlinear energy levels,so as to obtain two-level quantum bits.Then I show how to manipulate,couple,and measure qubits.Finally,two architecture methods of superconducting qubit chip are introduced briefly.In the third chapter,I take one of the Transmon-type superconducting qubits——Xmon used in our laboratory as an example to illustrate how to calibrate the basic parameters of superconducting qubits,including the S-parameter of cavities,qubit spectroscopy,readout parameters,decoherence time and the coupling strength between two qubits.In the fourth chapter,I introduce an eigensolver of digitized shortcut-to-adiabaticity(STA)and sequential digitized adiabaticity.This eigensolver was used in experiment to determine the potential energy landscape of hydrogen molecule efficiently and accurately.And I compare it with another quantum eigensolver——Variational Quantum Eigensolver and analyse their advantages,respectively.In chapter 5,I summarize this paper and look into the bright future of quantum computing.