单轴应变增强自旋轨道耦合实现超快速空穴自旋量子比特
Superfast hole spin qubits enabled by uniaxial strain-boosted spin-orbit coupling
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中文总结 AI 辅助
该研究利用CMOS工艺可实现的单轴应变增强Ge/SiGe量子阱的Rashba自旋轨道耦合，将空穴自旋量子比特拉比频率提升至40 GHz，进入抗电噪声的新区域，为提升量子比特性能提供了新方案。
中文摘要 AI 辅助
半导体异质结中受限的二维（2D）电子/空穴气存在Rashba自旋轨道耦合（SOC）较弱的问题，难以通过电场而非磁场操控自旋自由度。本文表明，互补金属氧化物半导体（CMOS）工艺可实现的应变能通过增强轻空穴与重空穴带的混合，大幅提升Ge/SiGe量子阱（QWs）中顶部空穴子带的线性Rashba SOC，达到与二维Rashba材料相当的水平。进一步研究显示，大幅增强的Rashba SOC使Ge/SiGe QWs中受限的空穴自旋量子比特的拉比频率提升两个数量级，达到前所未有的40 GHz，比其他量子比特平台快一个数量级以上。研究还证实，拉比频率>25 GHz的空穴自旋旋转进入了不受栅极控制引起的电噪声影响的新区域，为同时提升栅极速度和栅极保真度开辟了新途径。本研究为大幅提升二维半导体空穴气中的Rashba SOC至适合自旋电子学应用的水平提供了新途径。
英文摘要
Two-dimensional (2D) electron/hole gases confined in semiconductor heterostructures suffer from weak Rashba spin-orbit coupling (SOC) for manipulating spin degreee of freedom via an electric rather than a magnetic field. Here, we show that complementary metal-oxide-semiconductor technology-accessible strain could substantially enhance the linear Rashba SOC of the top hole subband in Ge/SiGe quantum wells (QWs) to a level comparable to that of 2D Rashba materials through enhancing the mixture of the light-hole and heavy-hole bands. We further show that strongly enhanced Rashba SOC boosts the Rabi frequency of hole spin qubits confined in Ge/SiGe QWs by two orders of magnitude to an unprecedented 40 GHz, more than one order of magnitude faster than other qubit platforms. We also demonstrate that the hole spin rotation with Rabi frequency > 25 GHz enters a new regime being immune to gate control-induced electric noise, opening a new avenue to simultaneously improve the gate speed and gate fidelity. Our findings provide a new routine to substantially enhance the Rashba SOC in 2D semiconductor hole gases to a level that is great for spintronic applications.
