Enhancement of the Kapitza conductance at 0.32 meV phonon energy

Using quasimonochromatic relaxation phonons emitted by superconducting tunneling functions, the phonon transfer through real solid-liquid helium interfaces was tested. We found an enhancement of the energy transmission if the incident phonons exceed the threshold energy Eo = 0.32 meV. This sharp threshold energy shifts to 0.42 meV if the lighter isotope 3 He is used

Chancen und Herausforderungen von DLT (Blockchain) in Mobilität und Logistik

This basic report presents the economic potential e, the legal framework and the technical fundamentals of distributed ledger or blockchain technology necessary for understanding in order to exploit the opportunities and challenges of these technologies, especially in the mobility and logistics sector. clear. The basic report was prepared on behalf of the Federal Ministry of Transport and Digital Infrastructure (BMVI) by the blockchain laboratory of Fraunhofer FIT

Opportunities and Challenges of DLT (Blockchain) in Mobility and Logistics

This report presents the economic potential, legal framework, and technical foundations required to understand distributed ledger (DL) / blockchain technology and llustrates the opportunities and challenges they present, especially in the mobility and logistics sectors. It was compiled by the blockchain laboratory at Fraunhofer FIT on behalf of the German Federal Ministry of Transport and Digital Infrastructure (BMVI). Its intended audience comprises young companies seeking, for example, a legal assessment of data protection issues related to DL and blockchain technologies, decisionmakers in the private sector wishing concrete examples to help them understand how this technology can impact existing and emerging markets and which measures might be sensible from a business perspective, public policymakers and politicians wishing to familiarize themselves with this topic in order to take a position, particularly in the mobility and logistics sectors, and members of the general public interested in the technology and its potential. The report does not specifically address those with a purely academic or scientific interest in these topics, although parts of it definitely reflect the current state of academic discussion

Polarization scramblers with plasmonic meander-type metamaterials

Due to plasmonic excitations, metallic meander structures exhibit an extraordinarily high transmission within a well-defined pass band. Within this frequency range, they behave like almost ideal linear polarizers, can induce large phase retardation between s- and p-polarized light and show a high polarization conversion efficiency. Due to these properties, meander structures can interact very effectively with polarized light. In this report, we suggest a novel polarization scrambler design using spatially distributed metallic meander structures with random angular orientations. The whole device has an optical response averaged over all pixel orientations within the incident beam diameter. We characterize the depolarizing properties of the suggested polarization scrambler with the Mueller matrix and investigate both single layer and stacked meander structures at different frequencies. The presented polarization scrambler can be flexibly designed to work at any wavelength in the visible range with a bandwidth of up to 100 THz. With our preliminary design, we achieve depolarization rates larger than 50% for arbitrarily polarized monochromatic and narrow-band light. Circularly polarized light could be depolarized by up to 95% at 600 THz

Analysis of hydrogen Rydberg spectra in a uniform magnetic field: uncovering the transition from regularity to irregularity in a real quantum system

Studies of the behaviour of quantum systems in a range of energy where their classical counterparts undergo transitions from regularity to irregularity, as manifested in phase space by the gradual destruction of invariant tori, to date have largely been confined to model Hamiltonian systems such as harmonic oscillators with cubic, quartic, or higher-degree polynomial corrections, or the stadium problem. We show that phenomena which have turned out characteristic of the onset of "quantum stochasticity" in these model systems can in fact be recovered in the quantal energy spectra of a "real" physical system, viz. spectra of hydrogen Rydberg atoms in strong magnetic fields. This implies that one has a simple prototype system at hand in which to study - not only in theory but also in experiment, quantitatively and in detail, and as a function of a continuously tunable external parameter - phenomena that are expected to be typical of the quantum properties of nonintegrable systems in general