Kolloquien

In recent years a wide range of novel and unusual semiconductors have been investigated as materials for optoelectronic devices. These include conjugated polymers, single-walled carbon nanotubes and quantum dots. Apart from their interesting electronic and optical properties they also enable new types of devices.   mehr...

Festkolloquium anlässlich der Verabschiedung von Prof. Dr. Ulrich Platt
Pioneered in the early seventies by Prof. Ulrich Platt and co-workers, the Differential Optical Absorption Spectroscopy (DOAS) has become a powerful and widely used method to probe the chemical composition of the atmosphere. The technique is based on the Beer-Lambert's law which relates the quantity of light absorbed in the atmosphere to the number of molecules in the light path.   mehr...

About a century after the development of quantum mechanics we have now reached an exciting time where non-trivial devices that make use of quantum effects can be built.   mehr...

The brain is a universe of 100 billion cells interacting through a constantly changing network of 1000 trillion synaptic connections. It runs on a power budget of 20 Watts and represents a rather complete model of our physical world.   mehr...

Entangled photons can now routinely be used in quantum communication over large distances exceeding 100 kilometers. I will review recent experiments, particularly in quantum teleportation and entanglement swapping on the Canary Islands. A novel possibility is given by photon states carrying orbital angular momentum.   mehr...

The stable generation of high temperature Hydrogen plasmas (ion and electron temperature in the range 10-20 keV) is the basis for the use of nuclear fusion to generate heat and thereby electric power. The most promising path is to use strong, toroidal, twisted magnetic fields to confine the electrically charged plasma particles in order to avoid heat losses to the cold, solid wall elements.   mehr...

Transparent materials can withstand optical peak field strengths in excess of 1 GV/m. With the help of transparent nanostructures, this large field strength can be utilized to build new particle accelerators. Much like in their classical RF brethrens, the charged particles interact with the electromagnetic driving field, which is shaped such that efficient particle acceleration takes place.   mehr...

100 years after Einstein’s completion of the general theory of relativity, physicists continue to struggle with finding a unified geometric description of all fundamental natural phenomena. String theory suggests that this “geometrization of physics” is inevitably intertwined with the reconciliation of gravity and quantum mechanics.   mehr...

Neutrinos are the second most numerous type of particle in the Universe. These almost “invisible” particles are incredibly difficult to detect, passing freely through matter.   mehr...

No matter in which culture, great religious feasts lead to opulent sweets and high level bakery art work resulting in cakes, cookies and other sweet delicious confectioneries. Star shaped cinnamon biscuits (Zimtsterne, “cinnamon stars”) almost everywhere in the world, Panettone in Italy, Stollen in Dresden, sugar pretzels or the classical “Hefezopf” (breaded yeast bun) define a class of sugar based foods with exceptional sweet taste, but very different mouth feel.   mehr...

Optically-trapped, ultra-cold gases of spin ½-up and spin ½-down ⁶Li atoms model high temperature superconductors, neutron matter, and even the quark-gluon plasma that existed microseconds after the Big Bang.   mehr...

For the past three years the Kilo-Degree Survey (KiDS) has been compiling a multi-colour map of part of the Southern sky, with the aim of studying the distribution of matter through gravitational lensing. Measurements such as these provide direct information on the growth of structure in the universe, and on the cosmological model.   mehr...

Lorentz symmetry is one of the cornerstones of modern physics. However, a number of theories aiming at unifying gravity with other fundamental interactions including string field theory suggest violation of Lorentz symmetry. While the energy scale of such strongly Lorentz symmetry-violating physics is much higher than that currently attainable by particle accelerators, Lorentz violation (LV) may nevertheless be detectable via precision measurements at low energies.   mehr...

Aus der Reihe Heidelberger Physiker berichten
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Das Alpha Magnet Spektrometer (AMS-02) ist ein Teilchendetektor auf der Internationalen Raumstation, der seit Mai 2011 die Flüsse der kosmischen Strahlung zwischen 0.5 GeV und einigen TeV mit bisher unerreichter Präzision vermisst. Highlights aus den ersten vier Jahren der Datennahme werden präsentiert.   mehr...