A new path for electron optics in solid-state systems

Date:
July 14, 2020
Source:
ETH Zurich Department of Physics
Summary:
In combined theoretical and experimental work, physicists
introduce and demonstrate a novel mechanism for electron optics
in two-dimensional solid-state systems. The discovery opens up
a route to engineering quantum-optical phenomena in a variety of
materials and devices.



FULL STORY ========================================================================== Electrons can interfere in the same manner as water, acoustical or
light waves do. When exploited in solid-state materials, such effects
promise novel functionality for electronic devices, in which elements
such as interferometers, lenses or collimators could be integrated for controlling electrons at the scale of mirco- and nanometres. However,
so far such effects have been demonstrated mainly in one-dimensional
devices, for example in nanotubes, or under specific conditions in two-dimensional graphene devices.

Writing in Physical Review X, a collaboration including the Department
of Physics groups of Klaus Ensslin, Thomas Ihn and Werner Wegscheider
in the Laboratory for Solid State Physics and Oded Zilberberg at the
Institute of Theoretical Physics, now introduces a novel general scenario
for realizing electron optics in two dimensions.


==========================================================================
The main functional principle of optical interferometers is the
interference of monochromatic waves that propagate in the same
direction. In such interferometers, the interference can be observed
as a periodic oscillation of the transmitted intensity on varying
the wavelength of the light. However, the period of the interference
pattern strongly depends on the incident angle of the light, and, as
a result, the interference pattern is averaged out if light is sent
through the interferometer at all possible incident angles at once. The
same arguments apply to the interference of matter waves as described
by quantum mechanics, and in particular to interferometers in which
electrons interfere.

As part of their PhD projects, experimentalist Matija Karalic
and theorist Antonio Strkalj have investigated the phenomenon of
electronic interference in a solid-state system consisting of two
coupled semiconductor layers, InAs and GaSb. They discovered that the
band inversion and hybridization present in this system provide a novel transport mechanism that guarantees non-vanishing interference even
when all angles of incidence occur. Through a combination of transport measurements and theoretical modelling, they found that their devices
operate as a Fabry-Pe'rot interferometer in which electrons and holes
form hybrid states and interfere.

The significance of these results goes firmly beyond the specific
InAs/GaSb realization explored in this work, as the reported
mechanism requires solely the two ingredients of band inversion
and hybridization. Therefore new paths are now open for engineering electron-optical phenomena in a broad variety of materials.


========================================================================== Story Source: Materials provided by
ETH_Zurich_Department_of_Physics. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Matija Karalic, Antonio Strkalj, Michele Masseroni, Wei Chen,
Christopher
Mittag, Thomas Tschirky, Werner Wegscheider, Thomas Ihn, Klaus
Ensslin, Oded Zilberberg. Electron-Hole Interference in an
Inverted-Band Semiconductor Bilayer. Physical Review X, 2020; 10
(3) DOI: 10.1103/ PhysRevX.10.031007 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200714132737.htm

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