• Observing the Birth of Quasiparticles in Real Time

    Researchers have studied quasiparticle dynamics in real time. IQOQI/Harald Ritsch

    The formation of quasiparticles, such as polarons, in a condensed-matter system usually proceeds in an extremely fast way and is very difficult to observe. In Innsbruck, Rudolf Grimm’s physics research group, in collaboration with an international team of theoretical physicists, has simulated the formation of polarons in an ultracold quantum gas in real time. The researchers have published their findings in the journal Science.

  • 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.

  • 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.

  • Unconventional quasiparticles predicted in conventional crystals

    Unconventional quasiparticles predicted in conventional crystals | Two electronic states known as Fermi arcs, localized on the surface of a material, stem out of the projection of a 3-fold degenerate bulk new fermion. Image: Science/AAAS

    An international team of researchers has predicted the existence of several previously unknown types of quantum particles in materials. The particles — which belong to the class of particles known as fermions — can be distinguished by several intrinsic properties, such as their responses to applied magnetic and electric fields. In several cases, fermions in the interior of the material show their presence on the surface via the appearance of electron states called Fermi arcs, which link the different types of fermion states in the material's bulk.