Xu Hongya, Huang Liang, Lai Ying-Cheng, Grebogi Celso
1] School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ 85287, USA [2] School of Physical Science and Technology and Key Laboratory for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou, Gansu 730000, China.
1] School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ 85287, USA [2] Department of Physics, Arizona State University, Tempe, Arizona 85287, USA [3] Institute for Complex Systems and Mathematical Biology, King's College, University of Aberdeen, Aberdeen AB24 3UE, UK.
Sci Rep. 2015 Mar 11;5:8963. doi: 10.1038/srep08963.
Persistent currents (PCs), one of the most intriguing manifestations of the Aharonov-Bohm (AB) effect, are known to vanish for Schrödinger particles in the presence of random scatterings, e.g., due to classical chaos. But would this still be the case for Dirac fermions? Addressing this question is of significant value due to the tremendous recent interest in two-dimensional Dirac materials. We investigate relativistic quantum AB rings threaded by a magnetic flux and find that PCs are extremely robust. Even for highly asymmetric rings that host fully developed classical chaos, the amplitudes of PCs are of the same order of magnitude as those for integrable rings, henceforth the term superpersistent currents (SPCs). A striking finding is that the SPCs can be attributed to a robust type of relativistic quantum states, i.e., Dirac whispering gallery modes (WGMs) that carry large angular momenta and travel along the boundaries. We propose an experimental scheme using topological insulators to observe and characterize Dirac WGMs and SPCs, and speculate that these features can potentially be the base for a new class of relativistic qubit systems. Our discovery of WGMs in relativistic quantum systems is remarkable because, although WGMs are common in photonic systems, they are relatively rare in electronic systems.
持续电流（PCs）是阿哈罗诺夫 - 玻姆（AB）效应最引人入胜的表现之一，已知对于存在随机散射（例如由于经典混沌）的薛定谔粒子，持续电流会消失。但对于狄拉克费米子来说情况仍然如此吗？由于最近对二维狄拉克材料的极大兴趣，解决这个问题具有重要价值。我们研究了由磁通量穿过的相对论量子AB环，发现持续电流极其稳健。即使对于存在完全发展的经典混沌的高度不对称环，持续电流的幅度与可积环的幅度处于同一数量级，因此有了超持续电流（SPCs）这一术语。一个惊人的发现是，超持续电流可归因于一种稳健的相对论量子态类型，即携带大角动量并沿边界传播的狄拉克回音壁模式（WGMs）。我们提出了一种使用拓扑绝缘体来观测和表征狄拉克回音壁模式和超持续电流的实验方案，并推测这些特性可能潜在地成为一类新型相对论量子比特系统的基础。我们在相对论量子系统中发现回音壁模式是很显著的，因为尽管回音壁模式在光子系统中很常见，但在电子系统中相对罕见。
