Information storage and transfer in the manner of simple ones and zeros—as
in today's classical computer technologies—is insufficient for quantum
technologies under development. Now, researchers from Japan have fabricated
a nanoantenna that will help bring quantum information networks closer to
practical use.
In a study recently published in Applied Physics Express, researchers from
Osaka University and collaborating partners have substantially enhanced
photon-to-electron conversion through a metal nanostructure, which is an
important step forward in the development of advanced technologies for
sharing and processing data.
Classical computer information is based on simple on/off readouts. It's
straightforward to use a technology known as a repeater to amplify and
retransmit this information over long distances. Quantum information is
based on comparatively more complex and secure readouts, such as photon
polarization and electron spin. Semiconductor nanoboxes known as quantum
dots are materials that researchers have proposed for storing and
transferring quantum information. However, quantum repeater technologies
have some limitations—for example, current ways to convert photon-based
information to electron-based information are highly inefficient. Overcoming
this information conversion and transfer challenge is what the researchers
at Osaka University aimed to address.
"The efficiency of converting single photons into single electrons in
gallium arsenide quantum dots—common materials in quantum communication
research—is currently too low," explains lead author Rio Fukai.
"Accordingly, we designed a nanoantenna—consisting of ultra-small concentric
rings of gold—to focus light onto a single quantum dot, resulting in a
voltage readout from our device."
The researchers enhanced photon absorption by a factor of up to 9, compared
with not using the nanoantenna. After illuminating a single quantum dot,
most of the photogenerated electrons weren't trapped there, and instead
accumulated in impurities or other locations in the device. Nevertheless,
these excess electrons gave a minimal voltage readout that was readily
distinguished from that generated by the quantum dot electrons, and thus
didn't disrupt the device's intended readout.
"Theoretical simulations indicate that we can improve the photon absorption
by up to a factor of 25," says senior author Akira Oiwa. "Improving the
alignment of the light source and more precisely fabricating the nanoantenna
are ongoing research directions in our group."
These results have important applications. Researchers now have a means of
using well-established nano-photonics to advance the prospects of upcoming
quantum communication and information networks. By using abstract physics
properties such as entanglement and superposition, quantum technology could
provide unprecedented information security and data processing in the coming
decades.
Reference:
Rio Fukai et al, Detection of photogenerated single electrons in a lateral
quantum dot with a surface plasmon antenna, Applied Physics Express (2021).
DOI: 10.35848/1882-0786/ac336d
Tags:
Physics