The intrinsic rotation of electrons - the "spin" - remains unused by modern electronics. If use as an information carrier were possible, the processing power of electronic components would suddenly increase to a multiple of the present capacity.
In cooperation with colleagues from Dortmund, St. Petersburg and Washington, Bochum physicists have now succeeded in aligning electron spin, bringing it to a controlled "waver" and reading it out. The electron spin can also be realigned as required at any time using optical pulses.
"This is the first, important step toward addressing these "quantum bits", which will form an integral part of data transfer systems and processors in the future", exclaimed Prof. Andreas Wieck. The researchers have published their report in NATURE Physics.
Complex Calculations in Minimum Space
The entirety of present day electronics is based on electrical charges: If a memory cell (bit) has an electrical charge, it represents a logical "1", if no charge is present this is a logical "0". However electrons have more than just a charge - they spin like a top around their own axis, producing a magnetic field, similar to the earth. This spin can be accelerated or decelerated by applying an external magnetic field. The "top" begins to waver and its axis tips to virtually any desired angle. If these manifold possibilities were used as information carriers, it would be possible to store a great deal more information than just "0" and "1" with an electron. Moreover adjacent electrons could be moved into various configurations, because they exert forces on one another in the same manner as two magnets on a bulletin board. This phenomenon would provide a significantly more complex base for data storage and processing. Even a small quantity of these so-call quantum bits (qubits), would allow extremely complex calculations, for which millions of bits are required today.
Confinement of Spins in Indium-Arsenic Islands
Naturally one single electron has only a very small measureable effect. For this reason individual electron measurements can only be performed with great difficulty using highly sensitive instruments. This is why the international research team has specialized in confining nearly one million electrons each in virtually identical indium-arsenic islands ("quantum dots") and totaling their effect. These "ensemble" measurements provide signals which are stronger by a magnitude of six, making them very sturdy and allowing them to be recorded easily.
"Contrary to the preconceptions of many international competitors, all associated electron spins exhibit precisely the same behavior and the microscopic effects can therefore be measured very easily" stated Wieck.
Optical Switching of Quantum Dots
In the study published in "NATURE" the physicists were not only successful in aligning the electron spin; they also managed to rotate it optically using a laser pulse in any desired direction at any time and read this direction out with a further laser pulse. This is the first important step towards "addressing" and influencing qubits. "The interesting factor here is that these electrons are enclosed in solid bodies, so we no longer need complex high vacuum equipment and light occlusion on all sides to keep them permanently in a module as in quantum optics " stressed Prof. Wieck. In Bochum the extremely high vacuum is required only once during production of the quantum dot; after that the semiconductor system is sealed against air ingress, has a long service life and is just as reliable as all transistors and memory cells already in use today.
A. Greilich, Sophia E. Economou, S. Spatzek, D. R. Yakovlev, D. Reuter, A. D. Wieck, T. L. Reinecke & M. Bayer: Ultrafast optical rotations of electron spins in quantum dots. in: NATURE Physics, 22.3.2009, DOI 10.1038/NPHYS1226
Prof. Dr. Andreas Wieck, Chair for Applied Solid State Physics at the Ruhr University in Bochum, Tel.: 0234/32-28786, E-Mail: email@example.com
Editor: Meike Drießen
Dr. Josef König | idw
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
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...
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...
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...
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....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
19.07.2018 | Earth Sciences
19.07.2018 | Life Sciences