Quantum emitters: Beyond crystal clear to single-photon pure

Date:
September 2, 2021
Source:
The Korea Advanced Institute of Science and Technology (KAIST)
Summary:
A research team has developed a technique that can isolate the
desired quality emitter by reducing the noise surrounding the
target with what they have dubbed a 'nanoscale focus pinspot.'


FULL STORY ========================================================================== Photons -- fundamental particles of light -- are carrying these words
to your eyes via the light from your computer screen or phone. Photons
play a key role in the next-generation quantum information technology,
such as quantum computing and communications. A quantum emitter, capable
of producing a single, pure photon, is the crux of such technology but has
many issues that have yet to be solved, according to KAIST researchers.


==========================================================================
A research team under Professor Yong-Hoon Cho has developed a technique
that can isolate the desired quality emitter by reducing the noise
surrounding the target with what they have dubbed a 'nanoscale focus
pinspot.' They published their results on June 24 in ACS Nano.

"The nanoscale focus pinspot is a structurally nondestructive technique
under an extremely low dose ion beam and is generally applicable for
various platforms to improve their single-photon purity while retaining
the integrated photonic structures," said lead author Yong-Hoon Cho from
the Department of Physics at KAIST.

To produce single photons from solid state materials, the researchers
used wide-bandgap semiconductor quantum dots -- fabricated nanoparticles
with specialized potential properties, such as the ability to directly
inject current into a small chip and to operate at room temperature
for practical applications. By making a quantum dot in a photonic
structure that propagates light, and then irradiating it with helium
ions, researchers theorized that they could develop a quantum emitter
that could reduce the unwanted noisy background and produce a single,
pure photon on demand.

Professor Cho explained, "Despite its high resolution and versatility,
a focused ion beam typically suppresses the optical properties around
the bombarded area due to the accelerated ion beam's high momentum. We
focused on the fact that, if the focused ion beam is well controlled,
only the background noise can be selectively quenched with high
spatial resolution without destroying the structure." In other words,
the researchers focused the ion beam on a mere pin prick, effectively
cutting off the interactions around the quantum dot and removing the
physical properties that could negatively interact with and degrade the
photon purity emitted from the quantum dot.

"It is the first developed technique that can quench the background
noise without changing the optical properties of the quantum emitter
and the built-in photonic structure," Professor Cho asserted.

Professor Cho compared it to stimulated emission depletion microscopy,
a technique used to decrease the light around the area of focus, but
leaving the focal point illuminated. The result is increased resolution
of the desired visual target.

"By adjusting the focused ion beam-irradiated region, we can select the
target emitter with nanoscale resolution by quenching the surrounding
emitter," Professor Cho said. "This nanoscale selective-quenching
technique can be applied to various material and structural platforms
and further extended for applications such as optical memory and high-resolution micro displays." Korea's National Research Foundation
and the Samsung Science and Technology Foundation supported this work.

========================================================================== Story Source: Materials provided by The_Korea_Advanced_Institute_of_Science_and_Technology_ (KAIST). Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Minho Choi, Seongmoon Jun, Kie Young Woo, Hyun Gyu Song, Hwan-Seop
Yeo,
Sunghan Choi, Doyoun Park, Chung-Hyun Park, Yong-Hoon Cho. Nanoscale
Focus Pinspot for High-Purity Quantum Emitters via Focused-Ion-Beam-
Induced Luminescence Quenching. ACS Nano, 2021; 15 (7): 11317 DOI:
10.1021/acsnano.1c00587 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210902124927.htm

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