Quantum circuit, developed at the Walther-Meissner-Institut (WMI), which can be used to produce restricted microwave states. Image: Andreas Battenberg / TUM

An international team headed by physicists from the Technical University of Munich (TUM) has, for the first time ever, experimentally implemented secure quantum communication in the microwave band in a local quantum network. The new architecture represents a crucial step on the road to distributed quantum computing. As of yet, there are no universal quantum computers in the world. But for the first time, an international team led by TUM physicists Rudolf Gross, Frank Deppe and Kirill Fedorov has successfully implemented secure quantum communication in a local network – via a 35-centimeter superconducting cable.

A quantum well narrows in the middle to a quantum point contact. Würzburg physicists have produced this device using new methods of nanostructuring. Picture: Christoph Fleckenstein / University of Wuerzburg

Physicists at the University of Würzburg have made a ground-breaking discovery: They have realized a fundamental nanoelectronic device based on the topological insulator HgTe previously discovered in Würzburg. Topological insulators are materials with astonishing properties: Electric current flows only along their surfaces or edges, whereas the interior of the material behaves as an insulator. In 2007, Professor Laurens Molenkamp at Julius-Maximilians-Universität (JMU) Würzburg in Bavaria, Germany, was the first who experimentally demonstrated the existence of such topological states. His team achieved this seminal work with quantum wells based on mercury and tellurium (HgTe). Since then, these novel materials have been the hope for a fundamentally new generation of components that, for example, promise innovations for information technology.

Energy transport in biomimetic nanotubes (left) and a three-dimensional spectrum (right). Bjoern Kriete (l.) / Stefan Mueller (r.)

It is crucial for photovoltaics and other technical applications, how efficiently energy spreads in a small volume. With new methods, the path of energy in the nanometer range can now be followed precisely. Plants and bacteria lead the way: They can capture the energy of sunlight with light-harvesting antennas and transfer it to a reaction centre. Transporting energy efficiently and in a targeted fashion in a minimum of space – this is also of interest to mankind. If scientists were to master it perfectly, they could significantly improve photovoltaics and optoelectronics.

Light pulses can form pairs in ultra-short pulse lasers. The pulse intervals (red) can be precisely adjusted by making certain changes to pump beam (green). Image: UBT.

Ultrashort laser pulses have enabled scientists and physicians to carry out high-precision material analyses and medical procedures. Physicists from the University of Bayreuth and the University of Göttingen have now discovered a new method for adjusting the extremely short time intervals between laser flashes with exceptional speed and precision. The intervals can be increased or decreased as needed, all at the push of a button. Potential applications range from laser spectroscopy to microscopy and materials processing. The researchers have now presented their latest findings in the journal Nature Photonics.