The connection known as quantum entanglement, which defies the laws of classical physics, will be tested over long distances for the first time in a series of experiments European researchers have proposed.
Albert Einstein called quantum entanglement “spooky action at a distance.” This phenomenon happens when two particles or objects become connected with each other so that changes affecting one of the objects will also affect the other, no matter how far apart they are.
The researchers plan to test this connection using the International Space Station (ISS) as it flies overhead. One of their experiments would involve attaching a special photon detector to a camera lens on the ISS.
“During a few months a year, the ISS passes five to six times in a row in the correct orientation for us to do our experiments,” said study co-author Rupert Ursin at the Austrian Academy of Sciences in a press release.
“We envision setting up the experiment for a whole week and therefore having more than enough links to the ISS available.”
They would create a pair of entangled photons and send one of them to the ISS camera while keeping the other one on the ground for measurement. Later, they would compare the measurements of the two photons.
“According to quantum physics, entanglement is independent of distance. Our proposed Bell-type experiment will show that particles are entangled, over large distances—around 500 km—for the very first time in an experiment,” Ursin said.
“Our experiments will also enable us to test potential effects gravity may have on quantum entanglement.”
In the other experiment, the researchers would use a stream of photons to send a secret encryption key from one place to another with the ISS as a relay point. This has been done with optical fibers on Earth, but never across such great distances.
The paper was published on April 9 in the New Journal of Physics.
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