Two-dimensional electrons confined to GaAs quantum wells are hallmark platforms for probing electron–electron interactions. Many key observations have been made in these systems as sample quality has improved over the years. Here, we present a breakthrough in sample quality via source-material purification and innovation in GaAs molecular beam epitaxy vacuum chamber design. Our samples display an ultra-high mobility of 44 × 10⁶ cm² V^–1 s^–1 at an electron density of 2.0 × 10¹¹ cm^–2. These results imply only 1 residual impurity for every 10¹⁰ Ga/As atoms. The impact of such low impurity concentration is manifold. Robust stripe and bubble phases are observed, and several new fractional quantum Hall states emerge. Furthermore, the activation gap (Δ) of the fractional quantum Hall state at the Landau-level filling (ν) = 5/2, which is widely believed to be non-Abelian and of potential use for topological quantum computing, reaches Δ ≈ 820 mK. We expect that our results will stimulate further research on interaction-driven physics in a two-dimensional setting and substantially advance the field.

限制在 GaAs 量子阱中的二维电子是探测电子-电子相互作用的标志性平台。随着多年来样品质量的提高，在这些系统中进行了许多关键观察。在这里，我们展示了通过源材料纯化和 GaAs 分子束外延真空室设计创新实现的样品质量突破。^{我们的样品在 2.0 × 10 11}  cm ^–2的电子密度下显示出 44 × 10 ⁶  cm ²  V ^–1  s ^–1的超高迁移率。这些结果意味着每 10 ^{10只存在 1 种残留杂质}Ga/As 原子。如此低的杂质浓度的影响是多方面的。观察到稳健的条纹和气泡相，并出现了几个新的分数量子霍尔态。此外，在朗道能级填充 ( ν ) = 5/2 时，分数量子霍尔态的激活间隙 ( Δ ) 达到Δ ≈ 820 ，这被广泛认为是非阿贝尔的，具有拓扑量子计算的潜在用途千克。我们期望我们的结果将激发对二维环境中交互驱动物理学的进一步研究，并显着推进该领域。