Quantum Physics

  • A Nano-Roundabout for Light

    Functional principle of a nano-roundabout.  © TU Wien

    At TU Wien, it was possible to create a nanoscale optical element that regulates the flow of light particles at the intersection of two glass fibers like a roundabout. A single atom was used to control the light paths. Just like in normal road traffic, crossings are indispensable in optical signal processing. In order to avoid collisions, a clear traffic rule is required. A new method has now been developed at TU Wien to provide such a rule for light signals. For this purpose, the two glass fibers were coupled at their intersection point to an optical resonator, in which the light circulates and behaves as in a roundabout. The direction of circulation is defined by a single atom coupled to the resonator. The atom also ensures that the light always leaves the roundabout at the next exit. This rule is still valid even if the light consists merely of individual photons. Such a roundabout will consequently be installed in integrated optical chips – an important step for optical signal processing.

  • Das MPQ päsentiert den Original-Laser

    Prof. Theodore Maiman (Foto: K. Maiman)

    Im Jahr 1960 begann eine neue Ära der Technologiegeschichte. Theodore Maiman stellte den ers-ten funktionierenden Laser der Öffentlichkeit vor. Ein kleines Gerät bestehend aus einer Blitzlampe, einem Rubinkristall und einer Hülse aus Metall. Maimans erster Laser hat die Jahrzehnte überdauert. Jetzt ist das Original im Foyer des Max-Planck Instituts für Quantenoptik (MPQ) in Garching b. München in einer kleinen Ausstellung zu sehen. Zusammen mit dem Laser präsentiert das MPQ das Original-Laborbuch von Theodore Maiman mit seinen bahnbrechenden Skizzen des Geräts. Die Ausstellung ist ab dem 12. Dezember 2016 kostenlos zu besichtigen am Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str.1, 85748 Garching; täglich von 9 bis 17 Uhr. Journalisten sind herzlich zur Ausstellungseröffnung am 12. Dezember 2016 um 15 Uhr im Foyer des MPQ eingeladen.

  • Deep Insight Into Interfaces

    Film of lanthanum cobalt oxide shows a sequence of positively and negatively charged atomic layers. Without electronic reconstruction an enormous electrostatic field would form between the layers Graphic: J.E. Hamann-Borrero & Vladimir Hinkov

    Interfaces between different materials and their properties are of key importance for modern technology. Together with an international team, physicists of Würzburg University have developed a new method, which allows them to have an extremely precise glance at these interfaces and to model their properties.

  • Further Improvement of Qubit Lifetime for Quantum Computers

    Illustration of the filtering of unwanted quasiparticles (red spheres) from a stream of superconducting electron pairs (blue spheres) using a microwave-driven pump. Philip Krantz, Krantz NanoArt

    New Technique Removes Quasiparticles from Superconducting Quantum Circuits - An international team of scientists has succeeded in making further improvements to the lifetime of superconducting quantum circuits. An important prerequisite for the realization of high-performance quantum computers is that the stored data should remain intact for as long as possible. The researchers, including Jülich physicist Dr. Gianluigi Catelani, have developed and tested a technique that removes unpaired electrons from the circuits. These are known to shorten the qubit lifetime (to be published online by the journal Science today.

  • Gravitationswellen als Sensor für Dunkle Materie

    Falls der Dunkle-Materie-Halo einer Galaxie aus einem Bose-Einstein-Kondensat (BEK) sehr leichter Teilchen besteht, werden durchgehende Gravitationswellen (GW), nicht aber Lichtwellen (γ) gebremst. Grafik: MPIK

    Die mit der Entdeckung von Gravitationswellen entstandene neue Disziplin der Gravitationswellen-Astronomie bekommt eine weitere Aufgabe: die Suche nach Dunkler Materie. Diese könnte aus einem Bose-Einstein-Kondensat sehr leichter Teilchen bestehen. Wie Rechnungen zeigen, würden Gravitationswellen gebremst, wenn sie durch derartige Dunkle Materie laufen. Dies führt zu einer Verspätung von Gravitationswellen relativ zu Licht, die bereits mit den heutigen Detektoren messbar sein sollte. Im Universum muss es gut fünfmal mehr unsichtbare als sichtbare Materie geben. Woraus diese Dunkle Materie besteht, ist immer noch unbekannt. Die experimentelle Suche konnte bisher nur Teilchenarten bzw. Energiebereiche ausschließen; gelegentliche Erfolgsmeldungen und Vermutungen ließen sich nicht verifizieren. Es sind aber noch längst nicht alle theoretischen Vorschläge überprüft.

  • 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”.

  • 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.

  • 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.

  • Studying fundamental particles in materials

    Stimulated by special laser pulses Weyl-cones dance in a Dirac-fermion material on a laser-controlled path (loop). One cone includes right-handed, the other left-handed Weyl-fermions.  Jörg M. Harms/MPSD

    Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales.

    Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity to observe particle properties that have no realization in elementary particles.

  • Traffic jam in empty space

    The Team of physicists in their laser laboratory (from left to right): Philipp Sulzer, Dr. Andrey Moskalenko, Dr. Denis Seletskiy, Maximilian Seeger, Dr. Claudius Riek, Prof. Alfred Leitenstorfer und Prof. Guido Burkard. Uni Konstanz

    New success for Konstanz physicists in studying the quantum vacuum. An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by Professor Alfred Leitenstorfer has now shown how to manipulate the electric vacuum field and thus generate deviations from the ground state of empty space which can only be understood in the context of the quantum theory of light.

  • Ultracold atoms in a "Rydberg-dress"

    Ultracold atoms in a Rydberg dress picture1 | Fig. 1: From the starting state densely filled with atoms (left), a ring-like structure emerges due to the long range interaction (right). Graphic: MPQ, Quantum Many-Body Systems Division

    Scientists at the MPQ (Garching) and MPIPKS (Dresden) have developed a novel technique to let atoms interact over large distances.

    Many properties of our everyday world can be explained if atoms are thought of as small, solid marbles, which feel each other only if brought in direct contact with each other. The temperature of the air surrounding us, for example, is the result of uncountable, continuously occurring collisions between its constituents. Contrary to this, we also know effects which arise from the interplay between two distant objects. Well-known examples are two magnets which can affect each other also at quite a distance, or the formation of a salt crystal as a regular arrangement of positively charged sodium and negatively charged chlorine ions, which are bound together at large distances by electrical attraction.

  • Ultrashort and Extremely Precise

    Innsbruck physicists observe a surprising quantum effect when short light pulses interact with matter. Patrick Maurer

    A group of theoretical physicists headed by Oriol Romero-Isart from the Institute for Quantum Optics and Quantum Information and the University of Innsbruck observes a surprising quantum effect when short light pulses interact with matter. In the future, this effect may be used for developing a completely new type of far-field light nanoscopes.