锗中翻转模式自旋量子比特的相干超低功耗电偶极自旋共振
Coherent and ultra-low-power EDSR with a flopping-mode spin qubit in germanium
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中文总结 AI 辅助
本研究在锗中实现翻转模式自旋量子比特，通过双量子点离域自旋，在低磁场下以超低功耗实现高保真单量子比特门操作，并揭示弛豫机制。
中文摘要 AI 辅助
半导体量子点中的空穴自旋量子比特能够实现高保真度的全电控制，但传统的电偶极自旋共振（EDSR）在有利于量子比特相干性和读出的低磁场下可能需要相当大的射频驱动功率。在平面锗空穴自旋量子比特中，器件上的驱动功率可达-27 dBm，这因发热和串扰对可扩展架构构成挑战。在此，我们展示了锗中的翻转模式（FM）量子比特，其中单个自旋离域在双量子点中，结合了对电荷噪声的一阶保护与异常高效的电力驱动。通过绘制相干甜点随磁场方向变化的图谱，我们实现了$T_2^*=1.4\mu\mathrm{s}$，$T_2^{\mathrm{Hahn}}=11.5\mu\mathrm{s}$，$T_2^{\phi,\mathrm{CPMG32}}=130\mu\mathrm{s}$和$T_1=226\mu\mathrm{s}$，并且在门时间$t_{X\pi}=88$ ns时单量子比特门保真度高达99.76$\\%$。重要的是，这些结果是在接近面内的5 mT磁场下，仅使用-52 dBm的器件驱动功率获得的。我们进一步发现，该区域中的量子比特弛豫与双光子Orbach过程一致，为进一步优化提供了途径。我们的结果表明，FM-EDSR支持超低功耗、高保真度的单量子比特操作，这些改进可能有益于可扩展的空穴自旋架构和混合自旋-光子界面。
英文摘要
Hole spin qubits in semiconductor quantum dots (QDs) enable high-fidelity all-electric control, but conventional electric dipole spin resonance (EDSR) can require substantial rf drive power at the low magnetic fields that are favorable for qubit coherence and readout. In planar Ge hole spin qubits, this can reach -27 dBm at the device, posing challenges for scalable architectures due to heating and crosstalk. Here, we demonstrate a flopping-mode (FM) qubit in Ge, where a single spin is delocalized in a double QD, combining first-order protection against charge noise with exceptionally efficient electric driving. By mapping out coherence sweet-spots as a function of magnetic field orientation we achieve $T_2^*= 1.4μ\mathrm{s}$, $T_2^{\mathrm{Hahn}}= 11.5 μ\mathrm{s}$, $T^{ϕ, \mathrm{CPMG32}}_2= 130 μ\mathrm{s}$, and $T_1= 226 μ\mathrm{s}$, and a single-qubit gate fidelity of up to 99.76$\%$ for a gate time $t_{Xπ} = 88$ ns. Importantly, these results are obtained at a nearly in-plane magnetic field of 5 mT using only -52 dBm drive power at the device. We further find that qubit relaxation in this regime is consistent with a two-photon Orbach process, providing a route for further optimization. Our results demonstrate that FM-EDSR supports ultra-low-power, high-fidelity single-qubit operations, improvements that could benefit scalable hole-spin-based architectures and hybrid spin-photon interfaces.
发表机构
- École Polytéchnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）
- Delft University of Technology（代尔夫特理工大学）
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