An experiment has shown that the spins of two electrons in a Cooper pair have a negative correlation – that they tend to point in opposite directions as predicted by the quantum theory of superconductivity. The observation was made by physicists in Switzerland and Italy and is claimed to be the first experimental confirmation of this effect.
Led by Arunav Bordoloi at the University of Basel, the team measured the spin correlation using a new spin-filter setup, which uses two quantum dots to extract Cooper pairs from a tiny piece of superconductor.
In the conventional description of superconductivity, electrons form Cooper pairs below a critical temperature. Unlike individual electrons, the pairs obey Bose–Einstein statistics and can therefore condense to form a collective superconducting state in which the charge-carrying electrons can flow without resistance.
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