Atoms

  • Kaiserslautern physicists observe diffusion of individual atoms in light bath

    First author Farina Kindermann and Professor Artur Widera in front of a quantum gas experi-mental setup for investigations on single atoms. University of Kaiserslautern/Thomas Koziel

    In a combination of experiments and theory the diffusion of individual atoms in periodic systems was understood for the first time. The interaction of individual atoms with light at ultralow temperatures close to the absolute zero temperature point provides new insights into ergodicity, the basic assumption of thermodynamics. Quantum physicists at University of Kaiserslautern have published their results together with colleagues in the renowned scientific journal “Nature Physics”.

  • Light-driven atomic rotations excite magnetic waves

    Light-driven atomic rotations (spirals) induce coherent motion of the electronic spins (blue arrows). Image: J.M. Harms/MPI for the Structure and Dynamics of Matter

    Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion. Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how the ultrafast light-induced modulation of the atomic positions in a material can control its magnetization. An international research team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter at CFEL in Hamburg used terahertz light pulses to excite pairs of lattice vibrations in a magnetic crystal.

  • Matter-antimatter symmetry confirmed with precision record

    Sketch of the experimental setup used at CERN for the determination of the antiproton-to-electron mass ratio. Graphic: Masaki Hori

    CERN experiment sets precision record in the measurement of the antiproton to electron mass ratio using a new innovative cooling technique. According to the Standard Model of elementary particle physics, to each particle exists an antiparticle that is supposed to behave exactly the same way. Thus, “anti-people” in an “anti-world” would observe the same laws of physics, or make the same experiences in general, as we do. This postulate is, however, difficult to prove, since it is almost impossible to perform measurements on antimatter: whenever an antiparticle meets is matter-counterpart, both particles annihilate, accompanied by the creation of energy.

  • Molekül-Motoren mit Licht-Antrieb

    Bahnbrechende Entwicklung: Zwei Nano-Maschinen (weiß) auf einer 8x8 Nanometer großen Kupferoberfläche (grau), aufgenommen bei -267° mit einem Rastertunnelmikroskop. In Gelb die Molekül-Modelle der Maschinen. Foto: Uni Graz/Grill

    ForscherInnen der Uni Graz steuern Nano-Maschinen auf Oberflächen. Ferngesteuerte Nano-Maschinen, angetrieben von einem Lichtstrahl, reinigen Oberflächen, bringen spezielle Pharmazeutika im Körper an ihren Zielort oder bauen elektronische Strukturen aus einzelnen Atomen. Dieser Zukunftsvision ist die Arbeitsgruppe von Univ.-Prof. Dr. Leonhard Grill vom Institut für Chemie der Karl-Franzens-Universität Graz einen großen Schritt nähergekommen: Dem Team ist es gelungen, einzelne molekulare Maschinen durch Laserlicht gezielt auf einer Oberfläche zu bewegen und währenddessen zu beobachten. Die Ergebnisse der Studie werden in der nächsten Ausgabe des Magazins „ACS Nano“ publiziert und sind online bereits veröffentlicht.

  • New Quantum States for Better Quantum Memories

    An artificial diamond under the optical microscope. The diamond fluoresces because due to a number of nitrogen defects. TU Wien

    How can quantum information be stored as long as possible? An important step forward in the development of quantum memories has been achieved by a research team of TU Wien. Conventional memories used in today’s computers only differentiate between the bit values 0 and 1. In quantum physics, however, arbitrary superpositions of these two states are possible. Most of the ideas for new quantum technology devices rely on this “Superposition Principle”. One of the main challenges in using such states is that they are usually short-lived. Only for a short period of time can information be read out of quantum memories reliably, after that it is irrecoverable.

  • Observing the birth of a spectral line

    Absorption in a helium as it depends on the photon energy of the exciting extreme-ultraviolet flash of light and the time delay to the ionizing near-infrared laser pulse acting as a cut-off gate. graphics: MPIK

    Ultrashort intense laser pulses cut into a fundamental quantum phenomenon.
    For the first time, physicists managed to observe in real time how an atomic spectral line emerges within the incredibly short time span of a few femtoseconds, verifying a theoretical prediction. This has been possible by applying a very fast temporal switch: An intense laser pulse cuts off the natural decay shortly after excitation by a preceding laser pulse. The build-up of the asymmetric Fano line shape of two quantum-mechanically interfering electrons in the Helium atom is measured by varying the time delay between the two laser pulses.

  • Quantum Particles Form Droplets

    Quantum droplets may preserve their form in absence of external confinement because of quantum effects. IQOQI/Harald Ritsch

    In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

  • Speeding up electronics with light

    Light pulses generate Multi-PHz electric current in bulk solids. The emitted extreme ultraviolet radiation allows scientists to record these electric currents in real time. Graphic: Research Group Attoelectronics, MPQ

    By using ultrafast laser flashes, scientists at Max Planck Institute of Quantum Optics generated and measured the fastest electric current inside a solid material. The electrons executed eight million billion oscillations per second, setting a record of human control of electrons inside solids! The performance of modern electronic devices such as computers or mobile phones is dictated by the speed at which electric currents can be made to oscillate inside their electronic circuits.

  • Ultrafast slow-motion microscope sees a single molecule vibrate

    Single pentacen molecules vibrate on a gold surface. Foto: Dominik Peller

    An international team of scientists based in Regensburg, Germany, has now recorded the ultrafast motion of a single molecule directly in time and space by combining a femtosecond laser with an atomic resolution microscope. Atoms and molecules are the constituents of virtually all matter that surrounds us. Interacting with each other while following the rules of nature, they form complex systems ranging from modern technology to living creatures. Their behavior, that is, what they actually do, basically determines all of natural and life sciences. They are so small, however, that we cannot observe them in daily life.