What Quantum computers can solve

Quantum computers are certainly not a direct replacement for traditional computers at this point and instead are far more efficient versus a traditional computer when dealing with large quantities of variables. ‘A common example is the “traveling salesman problem”, in this case there is a theoretical salesman who must visit varying numbers of cities which are all interconnected and hence have increasing number of possible routes to each destination. The issue becomes clear when viewing the time taken for a classical computer to determine the time a classical computer would take to determine the fastest route. Assuming the computer operated at 1GHz and using the algorithm R=(c -1)!’ (Whorl, N)

cities Routes (R=(c-1)!) Time (R/1x10^9)
2 1 1x10^-9 s
5 24 2.4x^-8 s
10 362880 3.628x10^-4 s
20 1.216x10^17 121600000s

Using 1 year = 3.2x10^7s, the time taken for a 1GHz computer to calculate the routes from 20 cities, would take 3.8 years. Here, the drawbacks of classical computing can be clearly seen, of course while this may be a ‘realistic’ argument, there are certainly more advanced algorithms to assume the fastest route, but as a way of presenting the inefficiency of a classical computer and its clear drawbacks to their use on very real situations such as global economics or for proofing large quantities of code for anomalies. In comparison a quantum computer would be able to solve a similar situation in minutes.

Aside from theoretical problems, quantum computers are readily available by a company named D-Wave. Their quantum computers contain 512 Qbits, (H) but are only able to affect the spin on 8 of these Qbits. Despite the extremely small amount of Qbits, the systems are proving to be extremely fast and “3,600”x faster in certain applications and tying with the 10th fastest super computer in the world. 'D-Wave systems are currently selling their initial machines and from the audience purchasing them such as NASA and Google, the scale of the problems that hope to be solved through quantum computing is truly immense as a mere 8 Qbits can store the 256 possible combinations achieved through binary transistors – simultaneously.' (BBC news 2014)

The aerospace company, Lockheed martin have purchased a quantum computer to check the software for their multiple aircraft and projects – with I giving the example of proofing the 24 million lines of code needed to land an F-35. (Weinberger, S)

Reference List

    Wohrl, N. (2014) Synthetic diamonds for the quantum computing revolution, Duisberg-Essen
    Schallar, B. (1996) The Origin, Nature, and Implications of "MOORE'S LAW"
    Bennett, H. (1996) Strengths and Weaknesses of Quantum Computing SIAM Journal on Computing, December
    Rowlatt J. (2014) Silicon: After the chip, another revolution?, BBC news, 2nd August
    Webb J. (2014) Purer-than-pure silicon solves problem for quantum tech, BBC news, 12 August
    (2014) Quantum phenomenon shown in $15m D-Wave computer, BBC news, 30th May
    Weinberger S. (2014) Why Google and the Pentagon want 'quantum computers', BBC news, 18th November