在预热多体自旋网络中的可调迈彭巴效应
Tunable Mpemba Effect in a Prethermal Many-Body Spin Network
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中文总结 AI 辅助
研究在金刚石中扩展无序的$^{13}$C核自旋网络的迈彭巴效应，通过场循环和弗洛凯驱动控制，观察到可重复的交叉并调交叉时间，半经典模拟揭示机制，证明反常弛豫，确定控制弛豫的资源。
中文摘要 AI 辅助
相互作用系统中的弛豫不仅取决于其与平衡态的初始距离，还取决于初始状态所激发的弛豫模式。在此，我们通过实验在金刚石中一个扩展的、无序的$^{13}$C核自旋网络中观察并控制了迈彭巴效应，即一个离平衡态更远的状态超过了一个初始时更近的状态。场循环使我们能够通过独立控制超极化和缺陷介导的弛豫来制备不同的空间极化分布。然后我们追踪它们在弗洛凯驱动下的演化，该驱动稳定了一个长寿命的预热状态。我们观察到可重复的迈彭巴交叉，并将交叉时间调整了几个数量级，从后期热化到预热平台期。半经典模拟表明，随机分布的顺磁缺陷会产生快速弛豫区域和支持最慢集体弛豫模式的缺陷贫乏区域。迈彭巴交叉由初始状态与该模式的重叠决定。我们的结果证明了在预热多体状态下的反常弛豫，并将无序、输运和模式选择性状态制备确定为控制扩展自旋网络中弛豫的资源。
英文摘要
Relaxation in an interacting system is determined not only by its initial distance from equilibrium, but also by the relaxation modes populated by the initial state. Here we experimentally observe and control the Mpemba effect, in which a state farther from equilibrium overtakes one initially closer, in an extended, disordered $^{13}$C nuclear-spin network in diamond. Field cycling allows us to prepare distinct spatial polarization profiles by independently controlling hyperpolarization and defect-mediated relaxation. We then track their evolution under Floquet driving, which stabilizes a long-lived prethermal regime. We observe reproducible Mpemba crossings and tune the crossing time over several orders of magnitude, from late-time thermalization into the prethermal plateau. Semiclassical simulations show that randomly positioned paramagnetic defects create fast-relaxing regions and defect-poor regions that support the slowest collective relaxation mode. The Mpemba crossings are set by the initial state overlap with this mode. Our results demonstrate anomalous relaxation within a prethermal many-body regime and identify disorder, transport, and mode-selective state preparation as resources for controlling relaxation in extended spin networks.
