Fabrication Of Josephson Parametric Amplifier And Research On Quantum Simulation In Superconducting Qubits System

Superconducting quantum computing has developed rapidly in recent years and the noisy intermediate-scale quantum(NISQ)systems have demonstrated quantum supremacy using specific algorithms.When superconducting quantum computing system is developing to a larger scale,there are still many problems that need to be solved.In order to optimize multi-bit multiplexed readout,we fabricated broadband Josephson parametric amplifiers,which improves the fidelity of qubit readout.We also used it to squeeze the vacuum fluctuations.At the same time,we used a noisy smallscale quantum system(3-10 qubits)to simulate Super Bloch oscillations and some nonHermitian phenomenon.The detailed research results of this thesis are as follows:We simplified our previous fabrication process,using the method of combination of niobium film and aluminum film to prepare some broadband Josephson parametric amplifiers more conveniently.The Josephson parametric amplifier fabricated by this process has a gain of over 15 d B,a gain bandwidth close to 400 MHz,a saturation power of-118 d Bm and a near-quantum-limited noise performance.The amplifiers have been used in multiple qubit devices and have exhibited their advantages in some experiments.We also used the fabricated Josephson parametric amplifier to achieve the squeezing of vacuum fluctuations with a squeezing level of 1.635 d B.We used a 10-qubit quantum processor to study the physical phenomenon of super Bloch oscillations.This is the first time that the phenomenon has been demonstrated in a superconducting quantum system.We have previously observed Bloch oscillations and Wannier-Stark localization in a 5-qubit quantum processor.Based on that,we have observed the Super Bloch oscillations by applying longitudinal fields to 10 qubits at the same time.We can adjust the drive strength,frequency and phase of the longitudinal fields to control the amplitude,period and spread direction of the super Bloch oscillations.We also constructed a non-Hermitian system with three flux qubits and two CPW resonanors.We have observed the quantum exceptional point and show the phenomenon of unidirectional transmission caused by symmetry breaking.We also tried building a second-order correlation measurement system based on GPU acceleration to detect the quantum properties of this non-Hermitian system.