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Quantum Entanglement Demonstrated Aboard Orbiting CubeSat

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An international research team led by the National University of Singapore (NUS) has generated and detected quantum entanglement onboard a CubeSat nanosatellite weighing less than 2.6 kg and orbiting Earth. CubeSats are low-resource, cost-effective satellites and are smaller than a shoebox.

As a first step, the researchers needed to demonstrate that a miniaturized photon source for quantum entanglement could remain intact through the stress of launch and operate successfully in the harsh environment of space within a satellite that provides minimal energy. They examined every component of the photon-pair source that would be used to generate quantum entanglement to see if it could be made smaller or more rugged.

Researchers developed a miniaturized source of quantum entanglement that measures only 20 by 10 cm. Courtesy of the Center for Quantum Technologies, National University of Singapore.

Researchers developed a miniaturized source of quantum entanglement that measures only 20 by 10 cm. Courtesy of the Center for Quantum Technologies, National University of Singapore.

“At each stage of development, we were actively conscious of the budgets for mass, size, and power," engineer Aitor Villar said. “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. To achieve high-quality entanglement, the researchers had to completely redesign the mounts that currently align the nonlinear crystals with a high degree of precision and stability.

To qualify the instrument for space, the researchers tested its ability to withstand the vibration and thermal changes experienced during a rocket launch and in-space operation. The photon-pair source maintained high-quality entanglement throughout the testing while preserving crystal alignment even after repeated temperature cycling from −10 to 40 °C.

The researchers incorporated their new instrument into SpooQy-1, a CubeSat that was deployed into orbit from the International Space Station on June 17, 2019. The instrument successfully generated entangled photon-pairs over temperatures from 16 to 21.5 °C.


The SpooQy-1 CubeSat contains a miniaturized quantum instrument that creates pairs of photons with the quantum property of entanglement. The entanglement is detected in correlations of the photons’ polarizations. Courtesy of the Center for Quantum Technologies, National University of Singapore, and NASA.
The SpooQy-1 CubeSat contains a miniaturized quantum instrument that creates pairs of photons with the quantum property of entanglement. The entanglement is detected in correlations of the photons’ polarizations. Courtesy of the Center for Quantum Technologies, National University of Singapore, and NASA.

“This demonstration showed that miniaturized entanglement technology can work well while consuming little power,” Villar said. “This is an important step toward a cost-effective approach to the deployment of satellite constellations that can serve global quantum networks.”

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

“In the future, our system could be part of a global quantum network transmitting quantum signals to receivers on Earth or on other spacecraft,” Villar said. “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.”

The research was published in Optica, a publication of OSA (The Optical Society) (www.doi.org/10.1364/OPTICA.387306). 

Published: July 2020
Glossary
quantum
The term quantum refers to the fundamental unit or discrete amount of a physical quantity involved in interactions at the atomic and subatomic scales. It originates from quantum theory, a branch of physics that emerged in the early 20th century to explain phenomena observed on very small scales, where classical physics fails to provide accurate explanations. In the context of quantum theory, several key concepts are associated with the term quantum: Quantum mechanics: This is the branch of...
quantum optics
The area of optics in which quantum theory is used to describe light in discrete units or "quanta" of energy known as photons. First observed by Albert Einstein's photoelectric effect, this particle description of light is the foundation for describing the transfer of energy (i.e. absorption and emission) in light matter interaction.
quantum entanglement
Quantum entanglement is a phenomenon in quantum mechanics where two or more particles become correlated to such an extent that the state of one particle instantly influences the state of the other(s), regardless of the distance separating them. This means that the properties of each particle, such as position, momentum, spin, or polarization, are interdependent in a way that classical physics cannot explain. When particles become entangled, their individual quantum states become inseparable,...
astronomy
The scientific observation of celestial radiation that has reached the vicinity of Earth, and the interpretation of these observations to determine the characteristics of the extraterrestrial bodies and phenomena that have emitted the radiation.
optical communications
The transmission and reception of information by optical devices and sensors.
cubesat
A CubeSat is a type of miniaturized satellite characterized by its standardized size and modular design. CubeSats are typically used for scientific research, technology demonstration, educational purposes, and commercial applications in space exploration. The CubeSat standard was developed to reduce the cost and complexity of satellite missions by providing a common platform for building and launching small satellites. Key features and characteristics of CubeSats include: Standardized...
nano
An SI prefix meaning one billionth (10-9). Nano can also be used to indicate the study of atoms, molecules and other structures and particles on the nanometer scale. Nano-optics (also referred to as nanophotonics), for example, is the study of how light and light-matter interactions behave on the nanometer scale. See nanophotonics.
Research & TechnologyeducationAsia-PacificEuropeNational University of Singaporequantumquantum opticsLight Sourcesquantum entanglementastronomyaerospaceoptical communicationsCommunicationsCubeSatPhoton SourcenanonanosatelliteTech Pulse

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