AI 中文总结
本研究提出一种基于双层Ge异质结构的可切换重空穴/轻空穴自旋量子比特，兼具两类量子比特优势，相干时间大幅提升，可实现快速单量子比特旋转与电荷噪声 sweet spot。
AI 中文摘要
平面SiGe/Ge异质结构中的压缩应变Ge量子阱是当前空穴自旋量子比特的先进平台，虽具有稳健的相干时间，但由于波函数的重空穴（HH）特性，其本征自旋轨道相互作用（SOI）较弱。近来，GeSn/Ge异质结构中提出了轻空穴（LH）量子比特，其具备强的、本征的、线性动量相关的SOI。本研究在含SiGeSn势垒的双层Ge异质结构中提出一种可切换HH-LH自旋量子比特，结合HH与LH器件的优势。该量子比特的特性可通过从LH阱输运至HH阱改变，此过程还能实现基于跳跃的快速单量子比特旋转。此外，研究观测到面内限域引入的HH-LH共振，产生g因子峰与一阶电荷噪声 sweet spot（ sweet spot可译为“ sweet spot”，此处保留专业术语）。计算显示，存在一个 sweet spot，其拉比频率约为100 MHz，与LH区域相当，但相干时间增加超十倍，约为100 μs。
英文摘要
Compressively strained Ge quantum wells in planar SiGe/Ge heterostructures are the state-of-the-art platform for hole spin qubits. While they exhibit robust coherence times, they possess weak intrinsic spin-orbit interaction (SOI) due to the heavy-hole (HH) character of the wavefunction. Recently, light-hole (LH) qubits were proposed in GeSn/Ge heterostructures, offering strong, intrinsic, linear-in-momentum SOI. In this work, we propose a switchable HH-LH spin qubit in a bilayer Ge heterostructure with SiGeSn barriers, combining the advantages of HH and LH devices. The character of the qubit can be changed by shuttling from an LH well to an HH well, which also enables fast, hopping-based single-qubit rotations. Additionally, we observe an HH-LH resonance introduced by the in-plane confinement, resulting in $g$-factor peaks and first-order charge noise sweet spots. Our calculations reveal a sweet spot with Rabi frequencies on the order of 100 MHz, comparable to the LH regime, but with a more than tenfold increase in coherence time, on the order of 100 $μ$s.
