Bristol researchers make quantum computing breakthrough

The team, from Bristol's Centre for Quantum Photonics, has shown that it is possible to recycle the particles inside a quantum computer, so that quantum factoring can be achieved with only one third of the particles originally required. Using photons as the particles, the researchers constructed a quantum optical circuit that recycled one of the photons to set a new record for factoring 21 with a quantum algorithm - all previous demonstrations have factored 15. Dr Anthony Laing, who led the project, said: "Quantum computers promise to harness the counterintuitive laws of quantum mechanics to perform calculations that are forever out of reach of conventional classical computers. Realising such a device is one of the great technological challenges of the century." While scientists and mathematicians are still trying to understand the full range of capabilities of quantum computers, the current driving application is the hard problem of factoring large numbers. The best classical computers can run for the lifetime of the universe, searching for the factors of a large number, yet still be unsuccessful. PhD student Enrique Martín-López, who performed the experiment, commented: "While it will clearly be some time before quantum computers hit the mainstream, this proof of principle experiment paves the way for larger implementations of quantum algorithms by using particle recycling."