Artistic visualisation of quantum entanglement in top-quarks. Image copyright CERN
A team of international scientists working on the ATLAS experiment, including experts from the University of Adelaide, has taken a major step forward in discovering more about quantum entanglement, one of the key properties underlying quantum physics.
"Entanglement is one of the properties described by quantum physics, and is one of the properties that scientists and engineers are trying to exploit to create new technologies, such as quantum computing," said the University of Adelaide's Professor Paul Jackson, School of Physics, Chemistry and Earth Sciences.
"The new development from the ATLAS experiment is that entanglement has been seen in pairs of particles called top quarks, where there are large amounts of energy in a very small space."
Quantum entanglement is a fascinating feature of quantum physics - the theory of the very small. If two particles are quantum-entangled, the state of one particle is tied to that of the other, no matter how far apart the particles are.
Professor Jackson is the National Contact Physicist for Australia on the ATLAS experiment, the largest general-purpose particle detector experiment, at the Large Hadron Collider, a particle accelerator at CERN in Geneva, Switzerland.
Professor Jackson and his colleagues from around the world test the fundamental forces of nature and search for new particles and phenomena. They analyse data from the ATLAS experiment in their search for a better understanding of how particles behave and how this can be applied.
"The top quark is the most massive of all fundamental particles, and its unusually large mass may be because it 'feels' a new force beyond the four we know exist, or is connected to other new phenomena in some way."Professor Paul Jackson, School of Physics, Chemistry and Earth Sciences, The University of Adelaide
"The top quark's very large mass makes it a good laboratory for studying entanglement - the new ATLAS measurement would not have been possible for the other five types of lighter quark," he explained.
There are six different kinds of quarks with a wide range of masses. Quarks are the only elementary particles to experience all the known forces of nature.
Entanglement enables quantum computers to perform multiple calculations simultaneously, implement various protocols and algorithms that are not possible with classical systems, and crucially to detect and correct errors in a way that is not possible for classical computers.
"But entanglement is also fragile. Currently, many quantum physics experiments are done at ultra-cold temperatures, to avoid 'bumping' the system and disturbing it," said Professor Jackson.
"Up to now, entanglement has been demonstrated in systems where scientists can set up the right conditions to make the measurements. However, this new measurement opens up a possibility for entanglement to be studied in the 'hot and noisy' environment created by particle colliders.
"A deeper understanding of the fundamental physics behind quantum technology is the key driver for impactful applications of quantum phenomena in everyday technologies."
The international team published their findings in the journal Nature.
