Re:New silicon structure opens the gate to quantum computers
by yorwba on Tuesday December 12, 2017 @08:53PM
(#15911358)
Quantum computing is certainly able to solve integer factorization and related problems (like breaking RSA encryption), just not for practical problem sizes yet.
You are probably thinking about NP-hard problems, which may or may not be solvable faster than on classical computers.
Re:New silicon structure opens the gate to quantum computers
by jcoffland on Wednesday December 13, 2017 @03:20AM
(#15912846)
Shor’s algorithm can factorize integers on a quantum computer asymptoticly faster than on a classical computer but the algorithm requires at least a 128 qubit quantum computer to factor a 128 bit number and thereby break something like 128 bit RSA encryption. No one yet has, or is publicly admitting to having, a reliable 128 qubit device.
In some cases, error correction can be achieved simply by running the algorithm a few times.
Re:New silicon structure opens the gate to quantum computers
by Beltiras on Wednesday December 13, 2017 @04:29AM
(#15913118)
Error correction is immaterial for the factoring case. You multiply the factors and if you do not get the original number you know you have to run it again.
Re:New silicon structure opens the gate to quantum computers
by jcoffland on Wednesday December 13, 2017 @01:02PM
(#15916009)
In Schor's algorithm, the quantum computer finds the period p of B mod N were N is the number you are trying to factor and B is a random number less than N. The quantum computer may find p with imperfect accuracy. Running the algorithm repeatedly can improve the accuracy of p. You can also try other numbers close to p. Both are examples of error correcting a quantum algorithm.
I thought it was still an open question as to whether a quantum computer would actually be able to solve this class of problems or not.
In addition, quantum computers have a great deal of noise--so quantum error correction seems to be a thing.