For years, cryptography that relies on the multiplication of large prime numbers, such as RSA encryption was thought to be extremely safe if not unbreakable. Bummer, because a quantum computer recently factored the number 15 using Shor’s algorithm. That computer was designed and built by researchers from MIT and a team at the University of Innsbruck. The secret: it uses lasers to manipulate five qubits implemented as five charged atoms.

Admittedly back in 2001 MIT manipulated a single molecule using nuclear magnetic resonance and used it to factor 15 using Shor’s algorithm, but the implementation was not scalable. Classical computers cannot generally factorise numbers efficiently because they have to do certain steps one after another. With a quantum computer, these steps, in some sense, are all running in parallel and thus notably faster.

Certain types of encryption use large prime numbers multiplied together. Given the resulting number, on conventional computers it takes months or years to factorise it back into the primes.

The research results are published in Science magazine as ‘Realization of a scalable Shor algorithm‘. I’d advise everyone to check their bank cards for dubious cash withdrawals in a place called Innsbruck.