论文标题
D-Wave量子退火器中的汉密尔顿噪声基准测试
Benchmarking Hamiltonian Noise in the D-Wave Quantum Annealer
论文作者
论文摘要
各种噪声来源通过以不受控制的方式改变量子计算机的性能，并减少其相干时间。在量子退火器中，这种噪声引入了定义原始问题的参数，以使他们发现与最初编程的问题扰动的问题的基础状态。在这里，我们描述了一种基准测定影响量子退火器编程的哈密顿量的噪声量的方法。我们表明，一系列退化的序列与编程的哈密顿量的系数为零，导致估计在量子退火方案中“原位”影响哈密顿参数的噪声光谱密度。该方法在D-Wave的低噪声2000 Qubit设备（DW_2000Q_6）中进行了证明，并在其最近发布的5000 QUBIT设备（Advantage_System1.1）中证明了该方法。我们对DW_2000Q_6的基准测试显示，汉密尔顿噪声以$ 1/f^{0.7} $频率依赖性特征固有的材料形成通量量子的材料固有的频率依赖性特征。相比之下，Advantage_System1.1被发现受到低退火时间的其他噪声源的影响，其基本的内在通量噪声幅度$ 2-3 $ $ 2-3 $ $ 2-3 $倍于所有退火时间的DW_2000Q_6。
Various sources of noise limit the performance of quantum computers by altering qubit states in an uncontrolled manner throughout computations and reducing their coherence time. In quantum annealers, this noise introduces additional fluctuations to the parameters defining the original problem Hamiltonian, such that they find the ground states of problems perturbed from those originally programmed. Here we describe a method to benchmark the amount of noise affecting the programmed Hamiltonian of a quantum annealer. We show that a sequence of degenerate runs with the coefficients of the programmed Hamiltonian set to zero leads to an estimate of the noise spectral density affecting Hamiltonian parameters "in situ" during the quantum annealing protocol. The method is demonstrated in D-Wave's lower noise 2000 qubit device (DW_2000Q_6) and in its recently released 5000 qubit device (Advantage_system1.1). Our benchmarking of DW_2000Q_6 shows Hamiltonian noise dominated by the $1/f^{0.7}$ frequency dependence characteristic of flux noise intrinsic to the materials forming flux qubits. In contrast, Advantage_system1.1 is found to be affected by additional noise sources for low annealing times, with underlying intrinsic flux noise amplitudes $2-3$ times higher than in DW_2000Q_6 for all annealing times.
