In the last of a three-part series on when quantum computers will change our lives, serial entrepreneur and co-founder of Amadeus Capital Partners Dr Hermann Hauser argues the moment of breakthrough is further away than we might hope.
I do believe quantum computers will be very important, but if I am asked ‘do I think they will make a difference in the very near future?’ – say within 10 years – I’d have to say no. There are both practical difficulties, in terms of developing effective hardware and software, as well as major commercial difficulties faced by quantum computing. Even if it comes to fruition, the impact will be very specialised: code cracking, or simulating quantum systems.
To just take the hardware, the largest number of qubits achieved so far is 14. The only instance of a quantum computer that produces interesting results is the machine built by D-Wave Systems, which is really more of a quantum simulation rather than a quantum computer. Having said that, there are now just beginning to be quantum gates with a fidelity good enough that will mean, with error correction, that it is possible to build a large computer – although it will be very expensive.
The second problem is that other than Shor’s algorithm, which is 20 years old, there is no algorithm that shows a really spectacular increase in performance. Shor’s algorithm has caused considerable anxiety among the spooks, because quantum computing could crack many of the cryptography codes we use to protect information, which are factorisation-based codes.
But quantum computers are Turing machines, so there is no problem that a quantum computer can solve that a classical computer cannot solve. There is no reason why at some time in the future we might not find a classical computing algorithm with the same efficiency. And although Shor’s algorithm shows efficiency gains, it is in a very restricted domain: code cracking. It can’t extend the usefulness of quantum computing to other areas.
Even if we can build the hardware, even if we find algorithms and software that works, there is still a steep hill to climb: it’s all very expensive. We’d need to reinvent the whole computing world – it would be fantastically difficulty commercialising it, because it is so expensive. Consequently the benefits we might get from quantum computers may be restricted to really quite esoteric domains.
I do believe that at some point we will start to see the impact of quantum computers but I don’t agree that you can ignore the practical difficulties. And the moment of breakthrough may be a little further away than some would have us believe.