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

Rydberg atoms in uniform magnetic fields: uncovering the transition from regularity to irregularity in a quantum system

We investigate the eigenvalue spectra of hydrogen Rydberg atoms in strong magnetic fields for manifestations of quantum stochasticity and find (i) a smooth transition from a Poisson-type to a Wigner-type distribution of level spacings in the range of energy where classical motion becomes increasingly chaotic, (ii) the occurrence of multiple avoided crossings, and (iii) connected with this, an extreme sensitivity of oscillator strengths, and thus of observable spectra, with respect to small variations of an external parameter, viz., the magnetic field strength

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