Researchers in Florence and Innsbruck have simulated a physical phenomenon in an atomic quantum gas that can also be observed at the edge of some condensed matter systems: chiral currents. The scientists have published the experiment, which will open new doors for the study of exotic states in condensed matter, in the journal Science.
Condensed matter physics remains a field of study with many puzzles to solve. New studies have become possible due to advances in experimental quantum physics.
In particular, ultracold atoms in optical lattices and an environment that is fully tunable and controllable represent an ideal system for studying the physics of condensed matter problems. One of these phenomena can be observed in connection with the quantum Hall effect:
When certain materials are subjected to a strong magnetic field, the electrons cannot move in a singular circular direction at the edges anymore but repeatedly bounce against the edge, where they are reflected. This corresponds to skipping trajectories. As a macroscopic consequence so called chiral currents, which move in the opposite direction at the opposite edges, can be observed at the boundaries of such two-dimensional materials.
“You could compare it to a river where the fish swim towards the right on one bank and towards the left on the other bank,” explains theoretical physicist Marcello Dalmonte from the Institute for Theoretical Physics at the University of Innsbruck and a member of Peter Zoller’s research group at the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences.
Already ten years ago, Peter Zoller’s research team proposed a way to simulate chiral currents with neutral atoms. This idea combined with the synthetic dimension approach, put forward by the Barcelona group at ICFO, was picked up and implemented by physicists at the European Laboratory for Nonlinear Spectroscopy (LENS) in Florence collaborating with theoretical physicists in Innsbruck.
In their experiment, the scientists confined an ultracold gas of ytterbium atoms in an optical lattice generated by laser beams. As it is difficult to reproduce the structure of two-dimensional condensed matter systems, the physicists use a new approach: They used a one-dimensional chain of atoms and produced the second dimension synthetically. The dynamics along the synthetic dimension are generated by laser-induced hopping between two or three internal spin states.
“From a theoretical perspective this hopping into different internal spin states represents the same concept as the geometrical hopping of electrons at the edges of a condensed matter system,” explains Marcello Dalmonte. Together with Marie Rider and Peter Zoller, Marcello Dalmonte laid the theoretical groundwork for the experiment and suggested how to observe this phenomenon.
The observations published in Science show that the particles move mostly to the right at one edge and to the left on the other edge. “This behavior is very similar to chiral currents known in condensed matter physics,” says Dalmonte. This simulation of exotic effects opens up new ways for the researchers to study other new physical phenomena, for example, in connection with quantum Hall effects, the study of anyons in atomic systems. These exotic quasi particles are suggested to being suitable as the main building block for topological quantum computers.
The researchers are supported, among others, by the Austrian Science Fund (FWF), the European Research Council (ERC) and the European Union.
Publikation: Observation of chiral edge states with neutral fermions in synthetic Hall ribbons. M. Mancini, G. Pagano, G. Cappellini, L. Livi, M. Rider, J. Catani, C. Sias, P. Zoller, M. Inguscio, M. Dalmonte, L. Fallani. Science, Vol. 349 no. 6255 pp. 1510-1513
Institute for Theoretical Physics
Universtity of Innsbruck and
Institute for Quantum Optics and Quantum Information
Austrian Academy of Sciences
Tel.: +43 512 507 4792
Dr. Christian Flatz
Tel.: +43 512 507 32022
Mobil: +43 676 872532022
http://www.uibk.ac.at/th-physik/qo/ - Quantum Optics Theory Group
http://www.uibk.ac.at/th-physik/ - Institute for Theoretical Physics, Universtity of Innsbruck
http://iqoqi.at/ - Institute for Quantum Optics and Quantum Information
http://Austrian Academy of Sciences
http://www.lens.unifi.it/ - European Laboratory for Nonlinear Spectroscopy (LENS)
Dr. Christian Flatz | Universität Innsbruck
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