A quantum computer, on the other hand, promises to factor a number of any size in one operation and, if one can be built, the future of the PKI looks bleak and we would have to find encryption methods that were safe against a quantum attack.

via A Quantum Computer Finds Factors.

Of course, factoring 15 isn’t something that is going to threaten the PKI and cryptography in general, but factoring larger numbers is just a matter of increasing the number of qubits and this approach does seem to be a scalable solid state approach.