Team realizes an Aharonov-Bohm type interferometer to measure the band topology in graphene type lattices

Team realizes an Aharonov-Bohm type interferometer to measure the band topology in graphene type lattices
Honeycomb lattice structure created by three intersecting laser beams (arrows). Credit: Chair of Quantum Optics, LMU

Among the most revolutionary concepts of modern physics is that the laws of nature are inherently non-local. One striking manifestation of this non-locality was famously predicted by Aharonov and Bohm: a magnetic field confined to the interior of a solenoid can alter the behavior of electrons outside it, shifting the phase of their wave-like interference although they never directly encounter the magnetic field.

Originally regarded as a mere curiosity, such "geometric phase shifts" are now known to have dramatic consequences for electron transport in solid-state materials, e.g., allowing unimpeded current flow along the edges of a material that is insulating in the bulk. In suitable crystalline structures, geometric phase shifts can arise even in the absence of any , instead induced by an elusive property known as "Berry flux" in momentum space that is difficult to measure directly.

Now, scientists at the Ludwig-Maximilians-Universität Munich, the Max Planck Institute of Quantum Optics and Stanford University have demonstrated a matter-wave interferometer that precisely measures Berry flux in an artificial crystal formed by a standing wave of light.

Their method, reported this week in Science Express may ultimately enable new approaches to quantum computation exploiting non-local, topological properties of matter for robust encoding of quantum information.

  • Team realizes an Aharonov-Bohm type interferometer to measure the band topology in graphene type lattices
    Credit: Lehrstuhl für Quantenoptik, LMU
  • Team realizes an Aharonov-Bohm type interferometer to measure the band topology in graphene type lattices
    Credit: Lehrstuhl für Quantenoptik, LMU

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More information: "An Aharonov-Bohm interferometer for determining Bloch band topology." Science DOI: 10.1126/science.1259052
Journal information: Science , Science Express

Citation: Team realizes an Aharonov-Bohm type interferometer to measure the band topology in graphene type lattices (2014, December 19) retrieved 17 June 2019 from https://phys.org/news/2014-12-team-aharonov-bohm-interferometer-band-topology.html
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