Single photons from a silicon chip
Novel source for quantum light particles

Date:
September 15, 2020
Source:
Helmholtz-Zentrum Dresden-Rossendorf
Summary:
Quantum technology holds great promise: Quantum computers are
expected to revolutionize database searches, AI systems, and
computational simulations. Today already, quantum cryptography
can guarantee secure data transfer, albeit with limitations. The
greatest possible compatibility with current silicon-based
electronics will be a key advantage. And that is precisely where
physicists have made progress: The team has designed a silicon-based
light source to generate single photons that propagate well in
glass fibers.



FULL STORY ========================================================================== Quantum technology holds great promise: Just a few years from now, quantum computers are expected to revolutionize database searches, AI systems,
and computational simulations. Today already, quantum cryptography can guarantee absolutely secure data transfer, albeit with limitations. The greatest possible compatibility with our current silicon-based electronics
will be a key advantage. And that is precisely where physicists from
the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and TU Dresden have made remarkable progress: The team has designed a silicon-based light source
to generate single photons that propagate well in glass fibers.


========================================================================== Quantum technology relies on the ability to control the behavior of
quantum particles as precisely as possible, for example by locking
individual atoms in magnetic traps or by sending individual light
particles -- called photons - - through glass fibers. The latter is
the basis of quantum cryptography, a communication method that is, in principle, tap-proof: Any would-be data thief intercepting the photons unavoidably destroys their quantum properties. The senders and receivers
of the message will notice that and can stop the compromised transmission
in time.

This requires light sources that deliver single photons. Such systems
already exist, especially based on diamonds, but they have one flaw:
"These diamond sources can only generate photons at frequencies that
are not suitable for fiber optic transmission," explains HZDR physicist
Dr. Georgy Astakhov. "Which is a significant limitation for practical
use." So Astakhov and his team decided to use a different material --
the tried and tested electronic base material silicon.

100,000 single photons per second To make the material generate the
infrared photons required for fiber optic communication, the experts
subjected it to a special treatment, selectively shooting carbon into the silicon with an accelerator at the HZDR Ion Beam Center. This created
what is called G-centers in the material -- two adjacent carbon atoms
coupled to a silicon atom forming a sort of artificial atom.

When radiated with red laser light, this artificial atom emits the
desired infrared photons at a wavelength of 1.3 micrometers, a frequency excellently suited for fiber optic transmission. "Our prototype can
produce 100,000 single photons per second," Astakhov reports. "And it
is stable. Even after several days of continuous operation, we haven't
observed any deterioration." However, the system only works in extremely
cold conditions -- the physicists use liquid helium to cool it down to
a temperature of minus 268 degrees Celsius.

"We were able to show for the first time that a silicon-based
single-photon source is possible," Astakhov's colleague Dr. Yonder
Berence'n is happy to report. "This basically makes it possible to
integrate such sources with other optical components on a chip." Among
other things, it would be of interest to couple the new light source with
a resonator to solve the problem that infrared photons largely emerge
from the source randomly. For use in quantum communication, however,
it would be necessary to generate photons on demand.

Light source on a chip This resonator could be tuned to exactly hit the wavelength of the light source, which would make it possible to increase
the number of generated photons to the point that they are available at
any given time. "It has already been proven that such resonators can be
built in silicon," reports Berence'n.

"The missing link was a silicon-based source for single photons. And
that's exactly what we've now been able to create." But before they can consider practical applications, the HZDR researchers still have to solve
some problems -- such as a more systematic production of the new telecom single-photon sources. "We will try to implant the carbon into silicon
with greater precision," explains Georgy Astakhov. "HZDR with its Ion Beam Center provides an ideal infrastructure for realizing ideas like this."

========================================================================== Story Source: Materials provided by
Helmholtz-Zentrum_Dresden-Rossendorf. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Michael Hollenbach, Yonder Berence'n, Ulrich Kentsch, Manfred Helm,
Georgy V. Astakhov. Engineering telecom single-photon emitters in
silicon for scalable quantum photonics. Optics Express, 2020; 28
(18): 26111 DOI: 10.1364/OE.397377 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200915105953.htm

--- up 3 weeks, 1 day, 6 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)