Design Of 8-Qubit Superconducting Quantum Computing Chip With Quantum Bus Architecture

Although classical computer can meet the needs of modern life and learning,it still has some limitations in calculation ability.By using the superposition and entanglement of quantum bits,some quantum algorithms can be constructed,and the computing speed of these quantum algorithms is much faster than that of electronic computers.In addition,quantum bits can also be used to simulate the properties of molecules and atoms,which is helpful to the research of materials and medicine.This thesis is based on the Xmon quantum bits,quantum bit selection,physical realization of quantum computers,parameter design of single qubit and multi-qubit chip layout design are studied.Meanwhile,a multiplex control scheme for multi-qubit system is proposed.The introduction part first introduces why we need a quantum computer based on the electronic computer.Then,a simple analysis is made on the existing qubits,and the reasons for choosing one of the qubits as the design elements are explained.Followed by an introduction to how to use the quantum algorithm to crack RSA password algorithm.Challenges in research of quantum computer are pointed out.Starting from the preparation process of Xmon qubit,we investigated the doublelayer photoresist technique and the double angle evaporation technique.After the chip package,it's put into the dilution refrigerator to be cooled.The spectrum test consists of the confirmation of qubit's existence,search of qubit's frequency and characterization of quantum energy spectrum,involving single photon and multi-photon transitions,photon number splitting effect,Vacuum Rabi splitting,dispersion measurement etc..The time domain test includes the characterization of the decoherence time of the qubit,which involves Rabi oscillation and spin echo test.Quantum algorithm can be realized by the combination of single qubit gates and an arbitrary general double bit quantum gate.This thesis focuses on how to design the layout size of superconducting quantum computing chip.Based on qubit's frequency and anharmonicity and the working principle of Josephson junction,we can derive Josephson energy and capacitor charging energy,which can be converted to oxidation time and cross capacitor size.Then,we started from the cavity quantum electrodynamics to research on the coupling coefficient between qubit and superconducting coplanar waveguide resonator,the coupling capacitance and the dimensions of capacitor's claw.On this basis,the length of the whole cavity is adjusted.Based on the design of a single qubit,different versions of the 8-qubit superconducting quantum computing chip are drawn,and the reasons for the design improvement are analyzed in detail.Based on the multi-qubit chip,this paper proposes a new multiplex control scheme for reducing the input port.At last,the limit number of tolerable Xmon quantum bits in a single layer wiring structure is analyzed.