论文标题
通过两级系统的工程噪声光谱稳定和改善量子的连贯性
Stabilizing and improving qubit coherence by engineering noise spectrum of two-level systems
论文作者
论文摘要
超导电路是量子计算的领先平台。但是，它们的连贯性时间仍然受到限制，并且会显示时间波动。这些现象通常归因于量子位和物质缺陷之间的耦合，这些缺陷可以很好地描述为两级系统（TLSS）的合奏。其中，无定形氧化物层内的电荷波动器均导致低频$ 1/f $电荷噪声和高频介电损失，从而造成快速量子的脱位和放松。此外，从相互TLS相互作用的光谱扩散会随着时间的流逝而变化噪声幅度，从而使量子寿命波动。在这里，我们建议通过设计相关的TLS噪声光谱密度来减轻这些有害影响。具体而言，我们的协议分别通过去极化和去除TLSS来平滑高频噪声谱并抑制低频噪声幅度。结果，我们预测量子寿命的剧烈稳定和量子纯dephasing时间的增加。我们对可行的实验实现的详细分析表明，通过从应用噪声到量子的伪造耦合，改进不会损害改善。
Superconducting circuits are a leading platform for quantum computing. However, their coherence times are still limited and exhibit temporal fluctuations. Those phenomena are often attributed to the coupling between qubits and material defects that can be well described as an ensemble of two-level systems (TLSs). Among them, charge fluctuators inside amorphous oxide layers contribute to both low-frequency $1/f$ charge noise and high-frequency dielectric loss, causing fast qubit dephasing and relaxation. Moreover, spectral diffusion from mutual TLS interactions varies the noise amplitude over time, fluctuating the qubit lifetime. Here, we propose to mitigate those harmful effects by engineering the relevant TLS noise spectral densities. Specifically, our protocols smooth the high-frequency noise spectrum and suppress the low-frequency noise amplitude via depolarizing and dephasing the TLSs, respectively. As a result, we predict a drastic stabilization in qubit lifetime and an increase in qubit pure dephasing time. Our detailed analysis of feasible experimental implementations shows that the improvement is not compromised by spurious coupling from the applied noise to the qubit.
