Kobayashi Kaito, Motome Yukitoshi
Department of Applied Physics, University of Tokyo, Tokyo, Japan.
Nat Commun. 2025 Apr 25;16(1):3871. doi: 10.1038/s41467-025-58751-0.
Quantum phase transitions are highly remarkable phenomena manifesting in quantum many-body systems. However, their precise identifications in equilibrium systems pose significant theoretical and experimental challenges. Thus far, dynamical detection protocols employing global quantum quenches have been proposed, wherein transitions are discerned via global nonequilibrium excitations. In this work, we demonstrate that quantum phase transitions can be detected through localized out-of-equilibrium excitations induced by local quantum quenches. While the resulting dynamics after the quench is influenced by both the local quench operation and the intrinsic dynamics of the quantum system, the effects of the former are exclusively extracted using the cutting-edge framework called quantum reservoir probing (QRP). Through the QRP, we find that the impacts of the local quenches vary across different quantum phases and are significantly suppressed by quantum fluctuations amplified near quantum critical points; consequently, phase boundaries are precisely delineated. We demonstrate that the QRP can detect quantum phase transitions in the paradigmatic integrable and nonintegrable quantum spin systems, and even topological quantum phase transitions, all within the identical framework employing local quantum quenches and single-site observables.
量子相变是量子多体系统中极为显著的现象。然而，在平衡系统中精确识别它们面临着重大的理论和实验挑战。到目前为止，已经提出了采用全局量子猝灭的动力学检测方案，其中通过全局非平衡激发来识别相变。在这项工作中，我们证明了量子相变可以通过局部量子猝灭诱导的局域非平衡激发来检测。虽然猝灭后的动力学受局部猝灭操作和量子系统固有动力学的共同影响，但前者的影响是通过称为量子库探测（QRP）的前沿框架专门提取的。通过QRP，我们发现局部猝灭的影响在不同量子相之间有所不同，并且在量子临界点附近放大的量子涨落会显著抑制这些影响；因此，可以精确描绘出相界。我们证明了QRP可以在使用局部量子猝灭和单格点可观测量的相同框架内检测典型的可积和不可积量子自旋系统中的量子相变，甚至拓扑量子相变。
