Coupling a Germanium Hut Wire Hole Quantum Dot to a Superconducting Microwave Resonator

Abstract

Realizing a strong coupling between spin and resonator is an important issue for scalable quantum computation in semiconductor systems. Benefiting from the advantages of a strong spin-orbit coupling strength and long coherence time, the Ge hut wire, which is proposed to be site-controlled grown for scalability, is considered to be a promising candidate to achieve this goal. Here we present a hybrid architecture in which an on-chip superconducting microwave resonator is coupled to the holes in a Ge quantum dot. The charge stability diagram can be obtained from the amplitude and phase responses of the resonator independently from the DC transport measurement. Furthermore, we estimate the hole-resonator coupling rate of g/2π = 148 MHz in the single quantum dot-resonator system and estimate the spin-resonator coupling rate g/2π to be in the range 2-4 MHz. We anticipate that strong coupling between hole spins and microwave photons in a Ge hut wire is feasible with optimized schemes in the future.

Semiconductor quantum computation

“…Also, it is free of valley degeneracy and thus supports the reproducibility of well defined qubits. Recent reports on quantum dots in Ge hut wires and the Ge/GeSi heterostructure have shown some initial results based on this material [ 56 , 60 , 177 ]. Further in-depth research is still needed to implement high-fidelity single- and two-qubit gates in such material and verify their homogeneity and reproducibility.…”

Ultrafast coherent control of a hole spin qubit in a germanium quantum dot

“…Hole spins provide an intriguing alternative for encoding qubits as compared to conduction electrons 18 – 21 , in particular in group IV materials such as Si and Ge 22 – 34 . Thanks to their underlying atomic P orbitals, which carry a finite angular momentum and have odd parity, holes experience an inherently strong SOI and weak hyperfine interaction 35 , 36 .…”

“…Here, we demonstrate an ultrafast control of a hole spin qubit on a Ge HW DQD [36][37][38]. By applying microwave bursts to one of the gates of the DQD and utilizing Pauli spin blockade (PSB) for spin-to-charge conversion, we observe a multi-mode electric-dipole spin resonance (EDSR) and two of them are used for spin manipulation.…”

Low-energy subband wave-functions and effective $g$-factor of one-dimensional hole gas

“…In recent years, hole spins confined in quasi one-dimensional (1D) Ge nanowire quantum dot are getting increasing attention. Quasi 1D hole gas can be realized in a Ge hut wire [36][37][38] or in a Ge/Si core-shell nanowire [39,40]. A quasi-1D quantum dot can be achieved by placing proper metallic gates bellow the 1D hole gas [18,19,41].…”