An international team directed by researchers from the Austrian Academy of Sciences, with participation from the Universitat Autònoma de Barcelona, has managed to create an entanglement of 103 dimensions with only two photons. The record had been established at 11 dimensions.
The states in which elementary particles, such as photons, can be found have properties which are beyond common sense. Superpositions are produced, such as the possibility of being in two places at once, which defies intuition. In addition, when two particles are entangled a connection is generated: measuring the state of one (whether they are in one place or another, or spinning one way or another, for example) affects the state of the other particle instantly, no matter how far away from each other they are.
Scientists have spent years combining both properties to construct networks of entangled particles in a state of superposition. This in turn allows constructing quantum computers capable of operating at unimaginable speeds, encrypting information with total security and conducting experiments in quantum mechanics which would be impossible to carry out otherwise.
In an article published this week in the journal Proceedings of the National Academy of Sciences (PNAS), scientists described how they managed to achieve a quantum entanglement with a minimum of 103 dimensions with only two particles. "We have two Schrödinger cats which could be alive, dead, or in 101 other states simultaneously", Huber jokes, "plus, they are entangled in such a way that what happens to one immediately affects the other". The results implies a record in quantum entanglements of multiple dimensions with two particles, established until now at 11 dimensions.
"This high dimension quantum entanglement offers great potential for quantum information applications. In cryptography, for example, our method would allow us to maintain the security of the information in realistic situations, with noise and interference. In addition, the discovery could facilitate the experimental development of quantum computers, since this would be an easier way of obtaining high dimensions of entanglement with few particles", explains UAB researcher Marcus Huber.
Now that the results demonstrate that obtaining high dimension [nexuses] is accessible, scientists conclude in the article that the next step will be to search how they can experimentally control these hundreds of spatial modes of the photons in order to conduct quantum computer operations.
