Studies On Hole Spin And Hybrid System Based On Ge Hut Wire Quantum Dots

For spin qubit-based quantum computing,the long coherence time and fast electrical controllability of the spin states are two key characteristics.Therefore,searching for suitable platform has become significant over the past few years.The group ? semiconductors,such as silicon(Si)and germanium(Ge),have predominantly stable isotopes with zero nuclear spin,which limits the hyperfine interaction,leading to a long dephasing time.Holes in Ge have an even weaker hyperfine interaction and a stronger spin-orbit interaction(SOI),which can be exploited for faster spin manipulation.However,to implement electron spin qubits in Si,an integrated component,such as a micromagnet or a strip line,has to be incorporated,which will complicate the fabrication process of such devices for spin control.Holes in Ge have a strong spin-orbit interaction,which can be exploited for fast and all-electrical control of the spin without any additional components.Therefore,the Ge quantum dots is an ideal platform for quantum computing.The main content of this thesis is outlined as follows:1.Introduced the research background of the Ge hole material system and some progress made so far,as well as the physical concepts of hole spin in semiconductor quantum dots and cavity quantum electrodynamics.2.The fabrication process of the Ge hut wire quantum dot device is described in detail,the relevant equipment and low-temperature measurement platform are introduced,the characterization method of the quantum dot is given,and the mobility of the Ge hut wire is evaluated.3.Fully tunable double quantum dots were prepared on the Ge hut wire,and the spin blockade phenomenon was observed.In the spin blockade regime,by analyzing the evolution of the leakage current with the magnetic field,it is confirmed that there is a strong spin-orbit coupling in the Ge hut wire system.We performed the electric dipole spin resonance experiments,and observed electric dipole spin resonance spectra in multiple modes.And the hole spin single bit of Ge hut wire was achieved and characterized.4.The dipole coupling of Ge hut wire hole double quantum dots and superconducting microwave resonator was realized.The charge states in the double quantum dots are detected by the microwave cavity and the tunable interdot tunneling rate and charge qubit decoherence rate were realized.The hole-resonator coupling strength was extracted and the hole spin-photon coupling strength in single quantum dots and double quantum dots were further evaluated.5.We introduced the site-controled Ge hut wire.Based on two adjacent parallel nanowires,a double quantum dot device with integrated charge sensor was fabricated.And use the charge sensor to detect the charge state of the double quantum dots.The innovations of this article include:1.The tunable Ge hut wire double quantum dot was fabricated for the first time.The spin-orbit coupling strength tso?38 ±4 ?eV was extracted and the spin-orbit coupling length lso?40-100 nm was evaluated.2.We observed the electric dipole spin resonance spectrum in multiple modes for the first time and analyzed its energy spectrum.3.Characterized the single hole spin qubit and obtained the fastest Rabi frequency fR?698±2 MHz?4.The coupling of Ge hut double quantum dots and superconducting microwave resonator is realized for the first time,the coupling strength gc/2??15 MHz.5.Based on the site-controled Ge hut wires,the capacitive coupling between double quantum dots and its neighboring charge sensors was realized for the first time,and the possibility of scalable quantum dots was explored.