Khomeriki Ramaz, Flach Sergej
Physics Department, Tbilisi State University, Chavchavadze 3, 0128 Tbilisi, Georgia.
Center for Theoretical Physics of Complex Systems, Institute for Basic Science, Daejeon 34051, South Korea.
Phys Rev Lett. 2016 Jun 17;116(24):245301. doi: 10.1103/PhysRevLett.116.245301. Epub 2016 Jun 15.
Sinusoidal Bloch oscillations appear in band structures exposed to external fields. Landau-Zener (LZ) tunneling between different bands is usually a counteracting effect limiting Bloch oscillations. Here we consider a flat band network with two dispersive and one flat band, e.g., for ultracold atoms and optical waveguide networks. Using external synthetic gauge and gravitational fields we obtain a perturbed yet gapless band structure with almost flat parts. The resulting Bloch oscillations consist of two parts-a fast scan through the nonflat part of the dispersion structure, and an almost complete halt for substantial time when the atomic or photonic wave packet is trapped in the original flat band part of the unperturbed spectrum, made possible due to LZ tunneling.
正弦布洛赫振荡出现在受到外场作用的能带结构中。不同能带之间的朗道 - 齐纳（LZ）隧穿通常是一种抵消效应，会限制布洛赫振荡。在这里，我们考虑一个具有两个色散带和一个平带的平带网络，例如用于超冷原子和光波导网络。通过使用外部合成规范场和引力场，我们得到了一个带有几乎平坦部分的受扰但无带隙的能带结构。由此产生的布洛赫振荡由两部分组成——快速扫过色散结构的非平坦部分，以及当原子或光子波包被困在未受扰光谱的原始平带部分时，在相当长的时间内几乎完全停止，这是由于LZ隧穿而成为可能。
