Quantum entanglement demonstrated aboard orbiting CubeSat
Advance poised to enable cost-effective space-based global quantum
network for secure communications and more

Date:
June 25, 2020
Source:
The Optical Society
Summary:
In a critical step toward creating a global quantum communications
network, researchers have generated and detected quantum
entanglement onboard a CubeSat nanosatellite weighing less than
2.6 kilograms and orbiting the Earth.



FULL STORY ==========================================================================
In a critical step toward creating a global quantum communications
network, researchers have generated and detected quantum entanglement
onboard a CubeSat nanosatellite weighing less than 2.6 kilograms and
orbiting the Earth.


==========================================================================
"In the future, our system could be part of a global quantum network transmitting quantum signals to receivers on Earth or on other
spacecraft," said lead author Aitor Villar from the Centre for Quantum Technologies at the National University of Singapore. "These signals could
be used to implement any type of quantum communications application, from quantum key distribution for extremely secure data transmission to quantum teleportation, where information is transferred by replicating the state
of a quantum system from a distance." In Optica, The Optical Society's
(OSA) journal for high impact research, Villar and an international group
of researchers demonstrate that their miniaturized source of quantum entanglement can operate successfully in space aboard a low- resource, cost-effective CubeSat that is smaller than a shoebox. CubeSats are a
standard type of nanosatellite made of multiples of 10 cm x 10 cm x 10
cm cubic units.

"Progress toward a space-based global quantum network is happening
at a fast pace," said Villar. "We hope that our work inspires the
next wave of space- based quantum technology missions and that new
applications and technologies can benefit from our experimental findings." Miniaturizing quantum entanglement The quantum mechanical phenomenon
known as entanglement is essential to many quantum communications
applications. However, creating a global network for entanglement
distribution isn't possible with optical fibers because of the optical
losses that occur over long distances. Equipping small, standardized
satellites in space with quantum instrumentation is one way to tackle
this challenge in a cost-effective manner.



==========================================================================
As a first step, the researchers needed to demonstrate that a miniaturized photon source for quantum entanglement could stay intact through the
stresses of launch and operate successfully in the harsh environment of
space within a satellite that can provide minimal energy. To accomplish
this, they exhaustively examined every component of the photon-pair
source used to generate quantum entanglement to see if it could be made
smaller or more rugged.

"At each stage of development, we were actively conscious of the
budgets for mass, size and power," said Villar. "By iterating the
design through rapid prototyping and testing, we arrived at a robust, small-form factor package for all the off-shelf components needed for
an entangled photon-pair source." The new miniaturized photon-pair
source consists of a blue laser diode that shines on nonlinear crystals
to create pairs of photons. Achieving high-quality entanglement required
a complete redesign of the mounts that align the nonlinear crystals with
high precision and stability.

Launching into orbit The researchers qualified their new instrument
for space by testing its ability to withstand the vibration and thermal
changes experienced during a rocket launch and in-space operation. The photon-pair source maintained very high- quality entanglement throughout
the testing, and crystal alignment was preserved even after repeated temperature cycling from -10 DEGC to 40 DEGC.

The researchers incorporated their new instrument into SpooQy-1, a CubeSat
that was deployed into orbit from the International Space Station on 17
June 2019.

The instrument successfully generated entangled photon-pairs over
temperatures from 16 DEGC to 21.5 DEGC.

"This demonstration showed that miniaturized entanglement technology
can work well while consuming little power," said Villar. "This is an
important step toward a cost-effective approach to the deployment of
satellite constellations that can serve global quantum networks." The
project was funded by Singapore's National Research Foundation.

The researchers are now working with RALSpace in the UK to design and
build a quantum nanosatellite similar to SpooQy-1 with the capabilities
needed to beam entangled photons from space to a ground receiver. This
is slated for demonstration aboard a 2022 mission. They are also
collaborating with other teams to improve the ability of CubeSats to
support quantum networks.


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


========================================================================== Journal Reference:
1. Aitor Villar, Alexander Lohrmann, Xueliang Bai, Tom Vergoossen,
Robert
Bedington, Chithrabhanu Perumangatt, Huai Ying Lim, Tanvirul
Islam, Ayesha Reezwana, Zhongkan Tang, Rakhitha Chandrasekara,
Subash Sachidananda, Kadir Durak, Christoph F. Wildfeuer,
Douglas Griffin, Daniel K. L. Oi, Alexander Ling. Entanglement
demonstration on board a nano-satellite. Optica, 2020; 7 (7):
734 DOI: 10.1364/OPTICA.387306 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200625102536.htm

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