Quantum physics is a strange science – according to it, light can exist as both a wave and a particle simultaneously, just observing a particle can change it, and – according to one interpretation – a cat can be alive and dead at the same time. As Richard Feynman said, “I think I can safely say that nobody understands quantum mechanics.” Yet, like any science, it will soon be used to advance technology.

Quantum computers are computers that use quantum properties to speed up computations. They are radically different from any type of digital computer. A bit in a classical computer can only be on or off. A quantum bit – a qubit – can be on, off, or on and off simultaneously. A collection of qubits can be in a great number of states at once, and thus do a huge amount of computations in parallel. The development of quantum computing is happening quickly – new advances are made almost every day.

People and banks don’t have to worry about transmitting important financial data online largely because of the protection provided by public-key cryptography. RSA, the most popular algorithm used to encrypt private data being sent across the Internet, has been shown to be impossible to break using even the fastest modern computers. Modern classical computers, that is.

It is possible for quantum computers to break RSA. Using a method known as Shor’s Algorithm – an algorithm specifically developed for quantum computers – an RSA key can be broken. Fast. Once quantum computers fast enough are created – which might not be far in the future – it won’t be much harder to break the code than it is to use it now. Despite that, RSA is still being used to encrypt a huge amount of personal data being sent in the open – even as quantum technology steadily advances. You might ask: “won’t RSA be replaced once quantum computers are developed?” It likely will, but what about the information that’s being transmitted right now, and in the near future? There’s no reason it can’t be recorded and decoded later, when technology is advanced enough – which might be as soon as in the next 10 years. Shor’s algorithm was already tested several times for simple cases on prototype quantum computers.

RSA is not the only algorithm to fall under quantum technology – other very popular algorithms such as Elliptic Curve Cryptography (ECC) and the Diffie-Hellman key exchange will also have to be replaced. But how quickly will they be replaced? It’s not easy to change such a basic aspect of online communication. Hundreds of protocols and likely tens of thousands of programs will have to be rewritten – and millions of people will have to be convinced to upgrade. Looking at how long it took for IE6 to be replaced, can we truly say we are ready for such a change?

Another article by me: Simulating Light – Inside Rendering Technology