Wang Ke, Elahi Mirza M, Wang Lei, Habib K M Masum, Taniguchi Takashi, Watanabe Kenji, Hone James, Ghosh Avik W, Lee Gil-Ho, Kim Philip
Department of Physics, Harvard University, Cambridge, MA 02138.
School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455.
Proc Natl Acad Sci U S A. 2019 Apr 2;116(14):6575-6579. doi: 10.1073/pnas.1816119116. Epub 2019 Mar 15.
We present a quantum switch based on analogous Dirac fermion optics (DFO), in which the angle dependence of Klein tunneling is explicitly utilized to build tunable collimators and reflectors for the quantum wave function of Dirac fermions. We employ a dual-source design with a single flat reflector, which minimizes diffusive edge scattering and suppresses the background incoherent transmission. Our gate-tunable collimator-reflector device design enables the quantitative measurement of the net DFO contribution in the switching device operation. We obtain a full set of transmission coefficients between multiple leads of the device, separating the classical contribution from the coherent transport contribution. The DFO behavior demonstrated in this work requires no explicit energy gap. We demonstrate its robustness against thermal fluctuations up to 230 K and large bias current density up to 10 A/m, over a wide range of carrier densities. The characterizable and tunable optical components (collimator-reflector) coupled with the conjugated source electrodes developed in this work provide essential building blocks toward more advanced DFO circuits such as quantum interferometers. The capability of building optical circuit analogies at a microscopic scale with highly tunable electron wavelength paves a path toward highly integrated and electrically tunable electron-optical components and circuits.
我们展示了一种基于类狄拉克费米子光学（DFO）的量子开关，其中明确利用了克莱因隧穿的角度依赖性来为狄拉克费米子的量子波函数构建可调准直器和反射器。我们采用了具有单个平面反射器的双源设计，该设计可将扩散边缘散射降至最低并抑制背景非相干传输。我们的栅极可调准直器 - 反射器器件设计能够在开关器件操作中对净DFO贡献进行定量测量。我们获得了器件多个引线之间的全套传输系数，将经典贡献与相干输运贡献区分开来。这项工作中展示的DFO行为不需要明确的能隙。我们证明了它在高达230 K的热波动和高达10 A/m的大偏置电流密度下，在很宽的载流子密度范围内具有鲁棒性。在这项工作中开发的可表征和可调谐光学组件（准直器 - 反射器）与共轭源电极相结合，为诸如量子干涉仪等更先进的DFO电路提供了基本构建模块。在微观尺度上利用高度可调谐的电子波长构建光学电路类比的能力为实现高度集成和电可调谐的电子光学组件及电路铺平了道路。
