Topological semimetals hosting bulk Weyl points and surface Fermi-arc states are expected to realize unconventional Weyl orbits, which interconnect two surface Fermi-arc states on opposite sample surfaces under magnetic fields. While the presence of Weyl orbits has been proposed to play a vital role in recent observations of the quantum Hall effect even in three-dimensional topological semimetals, actual spatial distribution of the quantized surface transport has been experimentally elusive. Here, we demonstrate intrinsic coupling between two spatially-separated surface states in the Weyl orbits by measuring a dual-gate device of a Dirac semimetal film. Independent scans of top- and back-gate voltages reveal concomitant modulation of doubly-degenerate quantum Hall states, which is not possible in conventional surface orbits as in topological insulators. Our results evidencing the unique spatial distribution of Weyl orbits provide new opportunities for controlling the novel quantized transport by various means such as external fields and interface engineering.

拥有大量Weyl点和表面费米弧态的拓扑半金属有望实现非常规的Weyl轨道，该轨道在磁场下将相对样品表面上的两个表面Fermi弧态相互连接。尽管Weyl轨道的存在已被证明在量子霍尔效应的最新观测中起着至关重要的作用，即使在三维拓扑半金属中也是如此，但是从表面上看，量化表面传输的实际空间分布在实验上是难以捉摸的。在这里，我们通过测量狄拉克（Dirac）半金属膜的双栅极器件，证明了Weyl轨道中两个空间分离的表面状态之间的固有耦合。顶栅电压和背栅电压的独立扫描显示了双简并量子霍尔态的伴随调制，这在常规表面轨道中是不可能的，在拓扑绝缘子中是不可能的。我们的研究结果证明了Weyl轨道的独特空间分布，为通过各种手段（例如外部场和界面工程）控制新颖的定量传输提供了新的机会。