半导体自旋梯中磁量子渡越的观测
Observation of magnetic quantum phase crossovers in a semiconductor spin ladder
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中文总结 AI 辅助
研究人员利用可编程海森堡自旋梯，通过哈密顿学习协议结合高阶自旋关联测量，观测到半导体自旋梯中的磁量子渡越，确立锗量子点阵列作为量子磁学可控平台，为研究掺杂体系非常规超导电性提供新途径。
中文摘要 AI 辅助
理解强关联量子磁体的集体相依赖于具有精确微观调控的理论可处理模型系统。反铁磁自旋梯提供了这样的体系，其在半填充时具有磁场可调的有能隙和无能隙相，掺杂时呈现非常规配对倾向。本研究中，我们在半填充的锗量子点阵列中实现了可编程海森堡自旋梯，该阵列具有空间分辨、连续可调的交换相互作用。在固定磁场下，我们改变梯级和链的耦合以绘制梯级单重态、倾斜反铁磁和完全极化相。结合平衡与动力学测量的哈密顿学习协议定量表征了该自旋梯，纳入自旋轨道相互作用以复现观测到的渡越行为。对高阶自旋关联函数（包括传统体探针无法获取的四点关联）的测量，揭示了有限尺寸下潜在相结构的特征。我们的结果确立了锗量子点阵列作为量子磁学的可控平台，为研究掺杂自旋梯中的非常规超导电性开辟了途径。
英文摘要
Understanding collective phases of strongly correlated quantum magnets relies on theoretically tractable model systems with precise microscopic control. Antiferromagnetic spin ladders provide such a setting, hosting field-tunable gapped and gapless phases at half filling and unconventional pairing tendencies upon doping. Here, we realize a programmable Heisenberg spin ladder in a half-filled germanium quantum dot array featuring site-resolved, continuously tunable exchange interactions. Under a fixed magnetic field, we vary the rung and leg coupling to map the rung-singlet, canted antiferromagnetic, and fully polarized phases. Hamiltonian-learning protocols combining equilibrium and dynamical measurements quantitatively characterize the ladder, incorporating spin-orbit interactions to reproduce the observed crossover behavior. Measurements of higher-order spin correlators -- including four-point correlations inaccessible to conventional bulk probes -- reveal signatures of the underlying phase structure despite the finite size. Our results establish germanium quantum dot arrays as a controllable platform for quantum magnetism, opening routes to investigate unconventional superconductivity in doped ladders.
