The demand for disorder-tolerant quantum logic and spin electronics can be met by generating and controlling dissipationless spin currents protected by topology. Dirac fermions with helical spin-locking surface transport offer a way of achieving such a goal. Yet, surface-bulk coupling can lead to strong Dirac electron scattering with bulk carriers and phonons as well as impurities, assisted by such dissipative channel, which results in “topological breakdown”. Here, we demonstrate that coherent lattice vibrations periodically driven by a single-cycle terahertz (THz) pulse can significantly suppress such dissipative channel in topological insulators. This is achieved by reducing the phase space in the bulk available for Dirac fermion scattering into during coherent lattice oscillations in Bi₂Se₃. This light-induced suppression manifests as a remarkable transition exclusively in surface transport, absent for bulk, above the THz electric fields for driving coherent phonons, which prolongs the surface transport lifetime. These results, together with simulations, identify the critical role of spin–orbit coupling for the “phase space contraction” mechanism that suppresses the surface-bulk coupling. Imposing vibrational quantum coherence into topological states of matter may become a universal light control principle for reinforcing the symmetry-protected helical transport.

通过生成和控制受拓扑保护的无耗散自旋电流，可以满足对无序耐受量子逻辑和自旋电子学的需求。具有螺旋自旋锁定表面传输的狄拉克费米子提供了实现这一目标的方法。然而，在这种耗散通道的辅助下，表面-体相耦合会导致散装载流子，声子以及杂质引起强烈的狄拉克电子散射，这会导致“拓扑结构崩溃”。在这里，我们证明了由单周期太赫兹（THz）脉冲周期性驱动的相干晶格振动可以显着抑制拓扑绝缘子中的这种耗散通道。这是通过在Bi _2的相干晶格振荡过程中将可用于狄拉克费米子散射的块中的相空间减少到最小来实现的硒₃。这种光诱导的抑制表现为显着的转变，完全在表面输运中，而不是在太赫兹电场之上以驱动相干声子，而对于表面输运来说是不存在的，这延长了表面输运寿命。这些结果与模拟一起，确定了自旋-轨道耦合对于抑制表面-本体耦合的“相空间收缩”机制的关键作用。将振动量子相干强加到物质的拓扑状态中可能成为增强对称性受保护的螺旋传输的通用光控制原理。