Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A quasiparticle collider

12.05.2016

Collision experiments in semiconductors come into reach

Our standard model of the smallest bits of matter rests upon evidence gathered from particle accelerators and collider experiments. A team of physicists from Regensburg (Germany), Marburg (Germany), and Santa Barbara (USA) have now realized a collider for particles in solids. This fundamentally new concept will be reported in the upcoming issue of Nature.


Electron (blue) and hole (red) are collided within a tungsten diselenide crystal (lattice at the bottom). The energy gained is released in high-energy photons (brightly coloured rays).

Fabian Langer

Already little children tend to smash all sorts of things together to learn about their interactions and properties. Particle colliders apply this natural idea to study the building blocks of matter. In the early 1900’s, Ernest Rutherford shot  α-particles onto gold foils and concluded from their scattering properties that atoms contain their mass in a very small nucleus. A hundred years later, the greatest collaboration in modern science smashed protons into each other in the pursuit and discovery of the Higgs boson.

Such an elemental collider concept is absent in solid-state research, although our modern technology crucially depends on knowing the structural and electronic properties of solids. In a crystal, the complex interaction of the billions upon billions of particles boils down to simple entities, so-called quasiparticles. However, it is extremely difficult to single out specific quasiparticles among a large ensemble of them.

A team of physicists from Germany and the US have now succeeded in smashing such elementary excitations of a solid into each other. Since the quasiparticles only exist for a flash of time, it was crucial to operate on ultrashort timescales. If one second was compared to the age of the universe, a quasiparticle would exist only for a few hours.

The scientists used a unique laser source (terahertz high-field lab, Regensburg) to produce hard evidence on collisions within excitons, which are pairs of electrons and holes (electron vacancies) bound by the attractive Coulomb-force between them, in a thin crystal of tungsten diselenide. A femtosecond optical pulse (1 femtosecond equals a millionth of a billionth of a second) creates excitons at a precise time with respect to an intense light pulse in the terahertz spectral regime (1 terahertz means one trillion oscillations per second).

The lightwave of the terahertz pulse accelerates the constituents of the exciton, i.e. electrons and holes, within a period shorter than a single oscillation of light. The experiment shows that only excitons created at the right time lead to electron–hole collisions, just as in conventional synchrotron accelerators. This re-collision generates ultrashort light bursts encoding key aspects of the solid. The observations in the laboratory are supported and explained by a quantum mechanical simulation carried out by physicists from the University of Marburg.

These time-resolved collision experiments in a solid prove that basic collider concepts can be utilized to transfer versatile methods from particle physics to solid-state research and shed new light on quasiparticles and many-body excitations in condensed matter systems. Ultimately, this approach might lead to the clarification of some of the most outstanding enigmas of condensed matter physics such as the binding mechanism of Cooper pairs in high temperature superconductors.

Original publication:
F. Langer, M. Hohenleutner, C. Schmid, C. Poellmann, P. Nagler, T. Korn, C. Schüller, M. S. Sherwin, U. Huttner, J. T. Steiner, S. W. Koch, M. Kira, and R. Huber, Lightwave-driven quasiparticle collisions on a sub-cycle timescale, Nature 2016
Publication: doi 10.1038/nature17958

Contact:
Prof. Dr. Rupert Huber
Universität Regensburg
Universitätsstraße 31
93053 Regensburg
Germany
E-Mail: rupert.huber@physik.uni-regensburg.de

Prof. Dr. Mackillo Kira
Philipps-Universität Marburg
Renthof 5
35032 Marburg
Germany
E-Mail: mackillo.kira@physik.uni-marburg.de

Alexander Schlaak | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-regensburg.de/

More articles from Physics and Astronomy:

nachricht Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>