The 10 nm limit

Mastery with an immediate outcome, the research's second major result: the measurements can be performed on the same sample! The experiment began with a wire that was much larger in size than the estimated limit (i.e. a superconductor), which was then reduced in size through several stages. "The width of the wire went from 70 nm to less than 10 nm and we managed to do better than that: at one point, we reduced the size of the wire to the width of one atom, i.e. the tenth of a nano!" The curves indicating the results show that the wire has a certain resistance in its normal state. When the transition temperature is reached, the resistance drops to zero (superconductivity, in the case of a 70 nm wire). 

For smaller widths, the transition temperature is no longer as well defined. The resistance decreases more slowly. As the wire becomes thinner, resistance decreases more slowly, until the point where it does indeed decrease, but never reaches 0 again.  Hence, the wire is never a superconductor again. This phenomenon occurs if the width is approximately 10 nm. "It's the limit between thermal and quantum fluctuations", Xavier Baumans points out. "As of this limit, the preponderant fluctuations are quantum. It doesn't matter how much you cool the circuit, its superconductivity will fade and disappear. Permanently".

The precise determination of the threshold value beyond which superconductivity ceases is the third major contribution of this researcher's work. Because superconducting circuits are much sought after by designers of future quantum computers. "Our research primarily serves as a warning", Xavier Baumans adds. "Superconductivity is essential but if we reduce the size of the circuits too much, this characteristic disappears… We have introduced a limit.  Although, I imagine a way will be found to overcome this limit".