The interaction of electrons and matter is fundamental to material properties such as electrical conductivity. Electrons are scattering from atoms of the surrounding matter and can excite lattice oscillations, so called phonons, thereby transferring energy to the environment. The electron is therefore slowed which causes electrical resistance.
University of Stuttgart, 5. Physikalische Institut
Illustration of the system investigated: A highly excited Rydberg-atom, consisting of a single electron (blue), traveling on a large orbit far from the positively charged core (red). The Rydberg atom has the same spatial extent as the ultracold atomic cloud. The single electron is exciting oscillations, so called phonons, in the surrounding quantum gas.
However, in certain materials phonons can surprisingly cause the opposite effect, so called superconductivity, where the electrical resistance drops to zero. Understanding the interaction of electrons and matter is therefore important goal in order to both answer fundamental questions as well as to solve technical problems.
A single electron is best suited for systematic investigations of such processes. For the first time, physicists from Stuttgart have now realized a model system in the laboratory, where the interaction of a single electron with many atoms inside its orbital can be studied. These atoms are from an ultracold cloud near absolute zero, a so called Bose-Einstein condensate.
The basic idea now is simple: Instead of using a technically challenging electron trap, the scientists are using the fact that in nature electrons are bound to a positively charged atomic core. In a classical picture, they are travelling on ellipsoidal orbits around the core. These orbits are usually very small, typically in the range below one nanometer. In order to achieve an interaction between an electron and many atoms, an atom is excited from a cloud consisting of 100.000 atoms using laser light.
The orbit of a single electron then expands to several micrometers and a Rydberg atom is formed. On atomic length scales, this atom is huge, larger than most bacteria, which are consisting each of + several billions to trillions of atoms. The Rydberg atom is then containing tens of thousands of atoms from the cold cloud. Thus, a situation is realized where the electron is trapped in a defined volume and at the same time interacts with a large number of atoms.
This interaction is so strong that the whole atomic cloud, consisting of 100,000 atoms is considerably influenced by the single electron. Depending on its quantum state the electron excites phonons in the atomic cloud, which can be measured as collective oscillations of the whole cloud culminating in a loss of atoms from the trap.
The experimental observations in the group of Prof. Tilman Pfau could so far largely be explained by collaborative work with the theory group of Prof. Hans Peter Büchler. However, this work is only the basis for a series of further exciting experiments. According to the previous studies an electron is leaving a clear trace in the surrounding atomic cloud. Therefore imaging a single electron in a well defined quantum state seems to be feasible. Due to the impact on various fields, including quantum optics, these results were published in the highly respected journal Nature *).
This work has been realized within Sonderforschungsbereich SFB/TRR 21 (Control of quantum correlations in tailored matter) and has been supported by the Detusche Forschungsgemeinschaft DFG and the European Research Council.
*) J.B. Balewski, A.T. Krupp, A. Gaj, D. Peter, H.P. Büchler, R. Löw, S. Hofferberth and T. Pfau, Coupling a single electron to a Bose-Einstein condensate; Nature, doi:10.1038/nature12592Further information:
Andrea Mayer-Grenu | idw
Study offers new theoretical approach to describing non-equilibrium phase transitions
27.04.2017 | DOE/Argonne National Laboratory
SwRI-led team discovers lull in Mars' giant impact history
26.04.2017 | Southwest Research Institute
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences