局域束和介质阻挡层

光子隧穿吸收介质势垒

Photon tunneling through absorbing dielectric barriers

利用最近发展起来的辐射量子化理论，研究了光子穿过吸收势垒的问题。多层屏障在频域中的多步复介电常数满足Kramers-Kronig关系。从由此产生的输入-输出关系，它示出的层中的损失可能会大大改变在双光子干涉实验中观察到的光子隧穿时间。它进一步表明，对于足够大的层数的干涉条纹观察到，不能涉及到一个单一的遍历时间。

Transmission time and resonant tunneling through barriers using localized quantum density soliton waves

In this paper, the interaction and transmission time of quantum density solitons waves representing particles passing through finite barrier potentials is investigated. Using the conservation of energy and of quantum density, it is first demonstrated that these waves have finite de Broglie wavelength and represent particles in quantum theory. The passage of the quantum density solitons (particles) through barriers of finite energies is then shown to lead to the phenomena of resonant tunneling and, in Josephson-like configurations, to the quantization of magnetic flux. A precise general measure…

Timescales of tunneling decay of a localized state

Motivated by recent time domain experiments on ultrafast atom ionization, we analyze the transients and timescales that characterize, besides the relatively long lifetime, the decay by tunneling of a localized state. While the tunneling starts immediately, some time is required for the outgoing flux to develop. This short-term behavior depends strongly on the initial state. For the initial state tightly localized so that the initial transients are dominated by over-the-barrier motion, the timescale for the flux propagation through the barrier is close to the Büttiker-Landauer traversal time. T…

Ge thin-films with tantalum diffusion-barriers for use in Nb-based superconductor technology

Germanium thin films are an excellent candidate for use as a low-loss dielectric in superconducting microwave resonators, a low-loss inter-layer metal wiring dielectric, and passivation layers in microwave and Josephson junction devices. In Ge/Nb structures deposited at 400 °C, we observe intermixing over as much as 20 nm. The addition of a 10 nm Ta diffusion barrier layer reduces the superconductor/dielectric intermixing to less than 5 nm and enhances the structural properties of deposited a-Ge layers based on Raman spectroscopy. Additionally, superconducting microwave resonators fabricated a…

Scattering and bound states by localized potentials

A simple formalism for exploring quantum scattering and possible bound states in an arbitrary symmetric and localized potential in a unified way is presented. The symmetric square barrier and well potentials are used for illustrating the method.