Quantum computing with recycled particles

October 23, 2012

A research team from the University of Bristol's Centre for Quantum Photonics (CQP) have brought the reality of a quantum computer one step closer by experimentally demonstrating a technique for significantly reducing the physical resources required for quantum factoring.

The team have shown how 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. The research is published in the latest issue of Nature Photonics.

Using photons as the particles, the Bristol team 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.

In fact, Internet cryptographic protocols are based on this exponential overhead in computational time: if a third party wants to spy on your emails, they will need to solve a hard factoring problem first. A quantum computer, on the other hand, is capable of efficiently factoring large numbers, but the physical resources required mean that constructing such a device is highly challenging.

CQP PhD student Enrique Martín-López, who performed the experiment, said: "While it will clearly be some time before emails can be hacked with a quantum computer, this proof of principle experiment paves the way for larger implementations of quantum algorithms by using particle recycling."
-end-
Paper: Experimental realization of Shor's quantum factoring algorithm using qubit recycling, Enrique Martín-López, Anthony Laing, Thomas Lawson, Roberto Alvarez, Xiao-Qi Zhou and Jeremy L. O'Brien, Nature Photonics, 21 October 2012.

University of Bristol

Related Quantum Computers Articles from Brightsurf:

Optical wiring for large quantum computers
Researchers at ETH have demonstrated a new technique for carrying out sensitive quantum operations on atoms.

New algorithm could unleash the power of quantum computers
A new algorithm that fast forwards simulations could bring greater use ability to current and near-term quantum computers, opening the way for applications to run past strict time limits that hamper many quantum calculations.

A new technique prevents errors in quantum computers
A paper recently published in Nature presents a protocol allowing for the error detection and the protection of quantum processors in case of qubit loss.

New method prevents quantum computers from crashing
Quantum information is fragile, which is why quantum computers must be able to correct errors.

Natural radiation can interfere with quantum computers
Radiation from natural sources in the environment can limit the performance of superconducting quantum bits, known as qubits.

New model helps to describe defects and errors in quantum computers
A summer internship in Bilbao, Spain, has led to a paper in the journal Physical Review Letters for Jack Mayo, a Master's student at the University of Groningen, the Netherlands.

The first intuitive programming language for quantum computers
Several technical advances have been achieved recently in the pursuit of powerful quantum computers.

Hot qubits break one of the biggest constraints to practical quantum computers
A proof-of-concept published today in Nature promises warmer, cheaper and more robust quantum computing.

Future quantum computers may pose threat to today's most-secure communications
Quantum computers that are exponentially faster than any of our current classical computers and are capable of code-breaking applications could be available in 12 to 15 years, posing major risks to the security of current communications systems, according to a new RAND Corporation report.

Novel error-correction scheme developed for quantum computers
Experimental quantum computers are plagued with errors. Here Dr Arne Grimsmo from the University of Sydney and colleagues from RMIT and the University of Queensland offer a novel method to reduce errors in a scheme applicable across different types of quantum hardware.

Read More: Quantum Computers News and Quantum Computers Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.