Quantum Physics

  • A Burst of ”Synchronous” Light

    Superlattices under the microscope (white light illumination). Empa

    Excited photo-emitters can cooperate and radiate simultaneously, a phenomenon called superfluorescence. Researchers from Empa and ETH Zurich, together with colleagues from IBM Research Zurich, have recently been able to create this effect with long-range ordered nanocrystal superlattices. This discovery could enable future developments in LED lighting, quantum sensing, quantum communication and future quantum computing. The study has just been published in the renowned journal "Nature".

  • 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.

  • An Acoustic Cage for Electrons

    In a piezo-electric solid (PE), counter-propagating surface-acoustic waves generate a time-dependent, periodic electric potential for electrons confined to a two-dimensional plane, i.e. a two-dimensional electron gas (2DEG); the resulting acoustic lattices are one- or two-dimensional, depending on the geometry of the setup. At high SAW frequencies, the potential can be effectively described by a time-independent pseudo-lattice. The motion of electrons at potential minima can be described by a harmonic oscillator, superimposed by small-amplitude, high-frequency micro-oscillations. (Graphic: from the original publication)

    International team of scientist develops new concept for trapping and manipulating electrons with sound waves. The ability to trap and control electrons and other quasi-particles for the study of isolated single particles as well as many-body systems in a solid-state environment can be of major importance for understanding the behaviour of correlated electrons in technologically relevant materials. Because of their – compared to atoms – extremely small masses, these point-like particles are very fast and mobile. This, however, makes them hard to hold in place.

  • Artificial Agent Designs Quantum Experiments

    The artificial agent uses optical elements such as this beam splitter to construct new and optimized experiments. Harald Ritsch

    On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

  • Attoseconds Break into Atomic Interior

    After the interaction of a xenon atom with two photons from an attosecond pulse (purple), the atom is ionized and multiple electrons (green balls) are ejected. This two-photon interaction is made possible by the latest achievements in attosecond technology. Graphic: Christian Hackenberger

    A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

  • Breaking Newton's Law

    Physicists have observed an intriguing oscillatory back-and-forth motion of a quantum particle in a one-dimensional atomic gas. Florian Meinert

    In the quantum world, our intuition for moving objects is strongly challenged and may sometimes even completely fail. Experimental physicists of the University of Innsbruck in collaboration with theorists from Munich, Paris and Cambridge have found a quantum particle which shows an intriguing oscillatory back-and-forth motion in a one-dimensional atomic gas. A ripe apple falling from a tree has inspired Sir Isaac Newton to formulate a theory that describes the motion of objects subject to a force. Newton’s equations of motion tell us that a moving body keeps on moving on a straight line unless any disturbing force may change its path. The impact of Newton’s laws is ubiquitous in our everyday experience, ranging from a skydiver falling in the earth's gravitational field, over the inertia one feels in an accelerating airplane, to the earth orbiting around the sun.

  • Breakthrough in Quantum Physics: Reaction of Quantum Fluid to Photoexcitation of Dissolved Particles

    Markus Koch (3rd from left), Bernhard Thaler (4th fro left), head of institute Wolfgang Ernst (far right) and team in the "Femtosecond-Laser-Lab" at the Institute of Experimental Physics at TU Graz. ©Lunghammer - TU Graz

    Researchers from Graz University of Technology have described for the first time the dynamics which takes place within a trillionth of a second after photoexcitation of a single atom inside a superfluid helium nanodroplet. In his research, Markus Koch, Associate Professor at the Institute of Experimental Physics of Graz University of Technology (TU Graz), concentrates on processes in molecules and clusters which take place on time scales of picoseconds (10⁻¹² seconds) and femtoseconds (10⁻¹⁵ seconds). Now Koch and his team have achieved a breakthrough in the research on completely novel molecular systems.

  • Breakthrough in spintronics

    Bismuthene film through the scanning tunnelling microscope. The honeycomb structure of the material (blue) is visible. A conducting edge channel (white) forms at the edge of the insulating film. Abbildung: Felix Reis

    It's ultra-thin, electrically conducting at the edge and highly insulating within – and all that at room temperature: Physicists from the University of Würzburg have developed a promising new material. The material class of topological insulators is presently the focus of international solids research. These materials are electrically insulating within, because the electrons maintain strong bonds to the atoms. At their surfaces, however, they are conductive due to quantum effects. 

  • Chiral Quantum Optics: A New Research Field with Bright Perspectives

    Surprising effect: directional emission of light  TU Wien

    Surprising direction-dependent effects emerge when light is guided in microscopic structures. This discovery shows promise for both classical and quantum information processing.

    Recently, surprising physical effects were observed using special microscopic waveguides for light. Such “photonic structures” currently are revolutionizing the fields of optics and photonics, and have opened up the new research area of “Chiral Quantum Optics”. Physicists from Copenhagen, Innsbruck, and Vienna, who are leading figures in this field, have now written an overview on the topic which just appeared in the scientific journal “Nature”.

  • Controlled Coupling of Light and Matter

    Artistic representation of a plasmonic nano-resonator realized by a narrow slit in a gold layer. Upon approaching the quantum dot (red) to the slit opening the coupling strength increases. Image: Heiko Groß

    Publishing in a journal like Science Advances usually heralds a particularly exciting innovation. Now, physicists from the Julius-Maximilians-Universität Würzburg (JMU) in Germany and Imperial College London in the UK are reporting controlled coupling of light and matter at room temperature. This achievement is particularly significant as it builds the foundations for a realization of practical photonic quantum technologies.

  • 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.

  • Electronic Highways on the Nanoscale

    In the Laboratory a structured silicon carbide crystal is heated in a preparation chamber of a scanning tunneling microscope, so that small graphene structures can be formed. Photo: TU Chemnitz/Jacob Müller

    For the first time, the targeted functionalization of carbon-based nanostructures allows the direct mapping of current paths, thereby paving the way for novel quantum devices. Computers are getting faster and increasingly powerful. However, at the same time computing requires noticeably more energy, which is almost completely converted to wasted heat. This is not only harmful to the environment, but also limits further miniaturization of electronic components and increase of clock rates. A way out of this dilemma are conductors with no electrical resistance.

  • Error-Free into the Quantum Computer Age

    Quantum error correction protocols detect and correct processing errors in trapped-ion quantum computers. IQOQI Innsbruck/Harald Ritsch

    A study carried out by an international team of researchers and published in the journal Physical Review X shows that ion-trap technologies available today are suitable for building large-scale quantum computers. The scientists introduce trapped-ion quantum error correction protocols that detect and correct processing errors. In order to reach their full potential, today’s quantum computer prototypes have to meet specific criteria: First, they have to be made bigger, which means they need to consist of a considerably higher number of quantum bits. Second, they have to be capable of processing errors.

  • Explanation for Puzzling Quantum Oscillations has been Found

    Ball bouncing chaotically in a stadium (top). If it starts near an unstable trajectory, it remains close to this trajectory for some time but eventually escapes (bottom). IST Austria/Maksym Serbyn

    So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics. Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a quantum simulator.

  • Exploring the Phenomenon of Superconductivity

    Types of pairing of two fermions. Figure: Puneet Murthy

    Fermions in flatland pair up at very high temperatures: Using ultracold atoms, researchers at Heidelberg University have found an exotic state of matter where the constituent particles pair up when limited to two dimensions. The findings from the field of quantum physics may hold important clues to intriguing phenomena of superconductivity. The results were published in Science magazine.

  • Fiber-based Quantum Communication - Interference of Photons Using Remote Sources

    Emission of single photons stemming from remote quantum dots. The wavelength of the single photons is manipulated by mixing them with strong laser fields within small crystals. University of Stuttgart/Kolatschek

    Scientists are working on the totally bug-proof communication – the so-called quantum communication. Current approaches for long-distance signal transmission rely on repeaters which are based on a crucial effect, the interference of two photons, that is, two individual light quanta coming from distant sources. Physicists from University of Stuttgart and Saarland University, in Germany, were now able to manipulate the single photons by means of small crystals without compromising their quantum mechanical nature. This manipulation is necessary to transmit the signal via optical fibers which may enable a large-area quantum network. The results were now published in Nature Nanotechnology.

  • First Single-photon Source that Works with Atomic Gases at Room Temperature

    Rubidium atoms are excited to their Rydberg states in a glass cell at room temperature. The volume between the glass plates is so thin that colored interference rings are visible to the naked eye. Universität Stuttgart/Max Kovalenko

    Researchers of the Center for Integrated Quantum Science and Technology IQST at the 5th Institute of Physics at the University of Stuttgart (Head: Prof. Tilman Pfau) have developed a novel, promising variant of a light source for the smallest possible energy packages - a so-called single-photon source. Their work has been published in the latest issue of the journal Science.*

  • 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.