Graf Anton M, Lin Ke, Kim MyeongSeo, Keski-Rahkonen Joonas, Daza Alvar, Heller Eric J
Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
Department of Physics, Harvard University, Cambridge, MA 02138, USA.
Entropy (Basel). 2024 Jun 5;26(6):492. doi: 10.3390/e26060492.
Recent theoretical investigations have revealed unconventional transport mechanisms within high Brillouin zones of two-dimensional superlattices. Electrons can navigate along channels we call superwires, gently guided without brute force confinement. Such dynamical confinement is caused by weak superlattice deflections, markedly different from the static or energetic confinement observed in traditional wave guides or one-dimensional electron wires. The quantum properties of superwires give rise to elastic dynamical tunneling, linking disjoint regions of the corresponding classical phase space, and enabling the emergence of several parallel channels. This paper provides the underlying theory and mechanisms that facilitate dynamical tunneling assisted by chaos in periodic lattices. Moreover, we show that the mechanism of dynamical tunneling can be effectively conceptualized through the lens of a paraxial approximation. Our results further reveal that superwires predominantly exist within flat bands, emerging from eigenstates that represent linear combinations of conventional degenerate Bloch states. Finally, we quantify tunneling rates across various lattice configurations and demonstrate that tunneling can be suppressed in a controlled fashion, illustrating potential implications in future nanodevices.
最近的理论研究揭示了二维超晶格的高布里渊区内存在非常规输运机制。电子可以沿着我们称为超线的通道行进，在没有强力限制的情况下被轻柔引导。这种动态限制是由弱超晶格偏转引起的，与传统波导或一维电子线中观察到的静态或能量限制明显不同。超线的量子特性导致弹性动态隧穿，连接相应经典相空间的不相交区域，并使得出现多个平行通道。本文提供了促进周期性晶格中由混沌辅助的动态隧穿的基础理论和机制。此外，我们表明，通过傍轴近似的视角可以有效地理解动态隧穿机制。我们的结果进一步揭示，超线主要存在于平带内，这些平带出自由代表传统简并布洛赫态线性组合的本征态。最后，我们量化了各种晶格构型的隧穿率，并证明隧穿可以以可控方式被抑制，这说明了其在未来纳米器件中的潜在应用。
