Spin correlation between paired electrons demonstrated
Physicists at the University of Basel have shown for the first time that there is a negative correlation between the spins of electrons from a superconductor
The researchers used spin filters made of quantum dots for their study, which was reported in the scientific journal Nature
The entanglement between two particles is hard to reconcile with everyday experiences in quantum physics
There are properties of the two particles that are linked if they are entangled. Einstein described the action of light particles at a distance as a "spooky action at a distance
Two electrons can be entangled. In a superconductor, the electrons form so-called Cooper pairs, which are responsible for the electrical currents and in which the individual spins are entangled
Researchers at the Swiss Nanoscience Institute and the Department of Physics at the University of Basel have been able to separate two electrons from a superconductor
Two quantum dots connected in parallel allow single electrons to pass, which is how this is achieved. Using an innovative experimental setup, the physicists were able to measure that the spin of one electron points upwards
The researchers used a spin filter in their laboratory to achieve this. They used tiny magnets to create magnetic fields in each of the two quantum dots that separated the Cooper pair electrons
The first author explains that we can adjust the quantum dots so that electrons with a certain spin pass through them. An electron with spin up and an electron with spin down pass through the same quantum dot, or vice versa
If both quantum dots are set to pass the same spins, the electric currents in both quantum dots are reduced even though an individual electron may well pass through a single quantum dot
We were able to detect negative correlations between electron spins from a superconductor for the first time, thanks to this method.
Our experiments are a first step, but not a definitive proof of entangled electron spins, since we cannot set the orientation of the spin filters
The research, which was recently published in Nature, is thought to be an important step towards further experimental investigations of quantum mechanical phenomena
the entanglement of particles in solids, which is also a key component of quantum computers.