When a computer can't handle multiplying two giant tables of numbers, they're sliced into tiny pieces and sent out to dozens of helper servers. For secret data, mathematical tricks are used so the helpers never see the original numbers. Usually, the higher the secrecy, the more servers you need.
The authors proposed using a special quantum property — entanglement between the servers.
Thanks to this, the servers, receiving only meaningless scraps, jointly compute the result. The number of servers is drastically reduced. Scientists worked out the optimal conditions and developed new families of codes.
The most surprising part: any attempt to eavesdrop instantly destroys the entanglement — data interception becomes pointless.
Cloud services will be able to process confidential data — bank calculations, medical analyses — quickly and reliably. Einstein, a skeptic of entanglement, would be amazed. The ideas of Charles Bennett turned quantum weirdness into a powerful tool for privacy.
With quantum entanglement, eavesdropping on a transmission is impossible: any attempt instantly destroys the link and gives the spy away.