Nano-scale Science and Engineering Center, University of California, Berkeley, CA 94720, USA.
Department of Electronic Engineering, Fudan University, Shanghai 200433, China.
Science. 2020 Dec 18;370(6523):1447-1450. doi: 10.1126/science.abe2011.
Tunneling plays an essential role in many branches of physics and has found important applications. It is theoretically proposed that Klein tunneling occurs when, under normal incidence, quasiparticles exhibit unimpeded penetration through potential barriers independent of their height and width. We created a phononic heterojunction by sandwiching two types of artificial phononic crystals with different Dirac point energies. The direct observation of Klein tunneling as shown by the key feature of unity transmission is demonstrated. Our experiment reveals that Klein tunneling occurs over a broad band of acoustic frequency. The direct observation of Klein tunneling in phononic crystals could find applications in signal processing, supercollimated beams, and communications.
隧道效应在物理学的许多分支中起着至关重要的作用，并找到了重要的应用。理论上提出，当准粒子在正常入射时，无论其高度和宽度如何，都能无阻地穿透势垒，从而发生 Klein 隧道效应。我们通过夹在两种具有不同狄拉克点能量的人工声子晶体之间，创建了一个声子异质结。通过证明传输率为 1 的关键特征，直接观察到 Klein 隧道效应。我们的实验表明，Klein 隧道效应发生在一个宽的声波频率范围内。在声子晶体中直接观察到 Klein 隧道效应可能在信号处理、超准直光束和通信中得到应用。
