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arXiv 2210.04539cond-mat.mes-hallquant-ph
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用于量子门保真度估计的半导体自旋量子比特及其电荷噪声环境建模

Modelling semiconductor spin qubits and their charge noise environment for quantum gate fidelity estimation

M. Mohamed El Kordy Shehata, George Simion, Ruoyu Li, Fahd A. Mohiyaddin, Danny Wan, Massimo Mongillo, Bogdan Govoreanu, Iuliana Radu, Kristiaan De Greve, Pol Van Dorpe

AI总结:

针对半导体自旋量子比特缺乏物理-量子比特能空间关联框架、电荷噪声致门误差的问题,提出双量子点与电荷噪声联合建模框架,揭示门误差与限制频率负相关等规律,为规模化自旋量子比特器件设计提供支撑。

摘要:

限制在半导体量子点中的电子自旋是当前量子比特(qubit)实现的极具前景的候选方案。借助现有的CMOS集成技术,这类器件可为大规模量子计算提供平台。然而,目前缺乏一种能将器件的物理设计与运行参数关联到量子比特能空间的量子力学框架。此外,由本征或诱导的自旋轨道相互作用(Spin-Orbit-Interaction, SOI)引入的自旋-电荷耦合,会使量子比特暴露于电荷噪声中,损害其相干特性并引发量子门误差。\n本文提出了一种针对双量子点(double quantum dot, DQD)器件及其电荷噪声环境的联合建模框架。我们结合静电势求解器、全组态相互作用量子力学方法以及两能级涨落子(two-level-fluctuator, TLF)模型,研究真实器件设计与运行条件下的量子门性能。我们利用所开发的模型以及量子点的单电子解,模拟了存在电荷噪声时的单量子比特与双量子比特门。研究发现,量子门误差与量子点限制频率之间呈负相关关系。在典型的TLF密度下,我们计算得到模拟的Si-MOS器件中的X门保真度高于97%。我们还发现,交换驱动的双量子比特SWAP门对电荷噪声的敏感性更高,在相同TLF密度下其保真度低至91%。我们进一步研究了不同TLF密度下的单、双量子比特门保真度。结果表明,由于量子点尺寸很小,量子门对噪声源与量子点之间距离的敏感性会导致量子门保真度出现强烈的波动,这可能会损害规模化量子比特技术中的器件良率。

英文摘要:

The spin of an electron confined in semiconductor quantum dots is currently a promising candidate for quantum bit (qubit) implementations. Taking advantage of existing CMOS integration technologies, such devices can offer a platform for large scale quantum computation. However, a quantum mechanical framework bridging a device's physical design and operational parameters to the qubit energy space is lacking. Furthermore, the spin to charge coupling introduced by intrinsic or induced Spin-Orbit-Interaction (SOI) exposes the qubits to charge noise compromising their coherence properties and inducing quantum gate errors. We present here a co-modelling framework for double quantum dot (DQD) devices and their charge noise environment. We use a combination of an electrostatic potential solver, full configuration interaction quantum mechanical methods and two-level-fluctuator models to study the quantum gate performance in realistic device designs and operation conditions. We utilize the developed models together alongside the single electron solutions of the quantum dots to simulate one- and two- qubit gates in the presence of charge noise. We find an inverse correlation between quantum gate errors and quantum dot confinement frequencies. We calculate X-gate fidelities >97% in the simulated Si-MOS devices at a typical TLF densities. We also find that exchange driven two-qubit SWAP gates show higher sensitivity to charge noise with fidelities down to 91% in the presence of the same density of TLFs. We further investigate the one- and two- qubit gate fidelities at different TLF densities. We find that given the small size of the quantum dots, sensitivity of a quantum gate to the distance between the noise sources and the quantum dot creates a strong variability in the quantum gate fidelities which can compromise the device yields in scaled qubit technologies.

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