A grand challenge underlies the entire field of {}-enabled quantum logic and information science: how to establish topological control principles driven by quantum coherence and understand the time-dependence of such periodic driving? Here we demonstrate a few-cycle THz pulse induced phase transition in a Dirac semimetal ZrTe${}_5$ that is periodically driven by vibrational coherence due to excitation of the lowest Raman-active mode. Above a critical THz pump field threshold, there emerges a long-lived metastable phase $$100ps with unique Raman phonon-assisted topological switching dynamics, absent for optical pumping. The switching also manifests itself by distinct features: non-thermal spectral shape, relaxation slowing down near the Lifshitz transition where the critical Dirac point (DP) occurs, and diminishing signals at the same temperature that the Berry curvature induced Anomalous Hall Effect (AHE) magneto-resistance varnishes. These results, together with first-principles modeling, identify a mode-selective Raman coupling that drives the system from strong to weak topological insulators, STI to WTI, with a Dirac semimetal phase established at a critical atomic displacement controlled by the phonon coherent pumping. Harnessing of vibrational coherence can be extended to steer symmetry-breaking transitions, i.e., Dirac to Weyl ones, with implications on THz topological quantum gate and error correction applications.

中文翻译：

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光驱动拉曼相干作为Dirac半金属超快拓扑切换的非热途径

巨大的挑战是{}-启用量子逻辑和信息科学的整个领域的基础：如何建立由量子相干性驱动的拓扑控制原理，以及如何理解这种周期性驱动的时间依赖性？在这里，我们展示了狄拉克半金属ZrTe中几个周期的THz脉冲诱导的相变${}_5$它是由最低拉曼激活模式的激发引起的振动相干周期性驱动的。高于临界THz泵浦场阈值时，会出现一个长寿命的亚稳态相位$ 100ps，具有独特的拉曼声子辅助拓扑转换动力学，而光泵浦则不存在。切换还以独特的特征表现出来：非热频谱形状，在临界Dirac点（DP）发生的Lifshitz跃迁附近的弛豫减慢，以及在与Berry曲率引起异常霍尔效应（AHE）相同的温度下信号衰减磁阻清漆。这些结果与第一原理建模一起确定了模式选择拉曼耦合，该耦合将系统从强拓扑绝缘体转变为弱拓扑绝缘体，从STI到WTI，与狄拉克半金属相建立在由声子相干泵浦控制的临界原子位移处。振动相干的控制可以扩展到控制破坏对称的过渡，即从狄拉克到魏尔，这对太赫兹拓扑量子门和纠错应用有影响。