Quantum dots are tiny traps for electrons, about the size of an atom, but artificially made. They can store and process information, like miniature cells of a future computer. Usually, to change the state of such a dot, you need to run a wire to it and apply a voltage. But in the new work, scientists showed that this can be done without direct contact — simply by acting on a neighboring dot.

Two quantum dots were connected through a superconductor — a material that carries current without loss. The result was an "Andreev molecule": electrons from one dot can pass into the other through the superconductor, and the states of the dots become linked. It turned out that if you change the state of one dot, the other switches too, even though no one touched it. The scientists found the conditions under which such switching happens reliably and figured out the rules governing this process.

The most interesting part is that the state of the system can be read out without additional sensors. You just measure the current through the superconductor: its magnitude changes depending on how the quantum dots are tuned. This simplifies the design of future quantum circuits. In the long run, such "molecules" could help build large quantum processors where elements interact at a distance, not just through direct connections.