矽基量子點中利用門組斷層掃描的隨機電荷雜訊模型

Abstract

無論是超導量子位元或是矽基量子點中的自旋量子位元，固態元件中的量子位元總是受到電荷雜訊的影響。傳統上我們將這些電荷雜訊當作二能階波動子群體，這導致系統的哈米爾頓量有隨機失諧頻率的雜訊。已經有針對這些隨機失諧雜訊的理論模型並且解釋固態系統中這些雜訊來源。然而當我們使用斷層掃描方法時，我們會發現除了原先的哈米爾頓工程錯誤產生器以外還有隨機包立錯誤產生器。我們在這篇文章中從與環境電荷雜訊分布耦合的量子位元來建立自旋玻色子模型。我們依然可以正確預測量子位元去相干的 𝑇∗2 時間，並成功預測隨機包立錯誤產生器。除此之外，我們也使用克羅托夫演算法來優化我們的量子閥操作並將全去相干雜訊的不保真度從 0.017% 降低到 0.0023%，低於了容錯量子計算的門檻。

Regardless of superconductor qubits or spin qubits in silicon quantum dots, qubits in solid state devices suffer from charge noise. Traditionally, this charge noise is modeled coming from a 2-level fluctuator ensemble, leading to random detuning noise on the system Hamiltonian. There have been some theoretic models corresponding with this random detuning noise and explaining the noise source in solid state devices. However, when we start using the tomography method, we then observe that there is another stochastic Pauli error generator besides the original Hamiltonian engineering error generators. Here, we start with qubits in a silicon-based quantum-dot system coupled with an environmental charge noise distribution to construct a spin-boson model. Employing this spin-boson model, we can still predict the 𝑇 ∗2 time relating to qubit decoherence correctly and also simulate the stochastic Pauli error generator successfully. Moreover, we also use the Kirov algorithm to optimize our gate operation and suppress the infidelity of full incoherent noise from 0.017% to 0.0023% below the surface code error threshold required for fault-tolerant quantum computing.