Diamond based quantum computers a step closer to reality
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Researchers in Tokyo and Vienna have proposed a new architecture which they believe would support a scalable quantum computer based on spins of nitrogen atoms in diamonds.
For decades, scientists have been trying to use quantum systems for logical calculations.
"In a classical computer, one bit can only store a number: zero or one," explained Jörg Schmiedmayer, of the Technical University of Vienna. "Quantum physics, however, allows superpositions of states. A quantum bit can be in the state zero and the state one at the same time – and this opens up unbelievable possibilities for computing."
The researcher's architecture uses nitrogen atoms that can occupy two spin states, injected into a diamond, with each nitrogen defect trapped in an optical resonator made of two mirrors.
Photons are coupled to the quantum system consisting of the resonator, the diamond and the nitrogen atom via glass fibres. This makes it is possible to read and manipulate the state of the quantum system without destroying the quantum properties of the spins in the diamond.
Each system – made up of mirrors, diamond and a nitrogen defect – can store one quantum bit of information: zero, one, or an arbitrary superposition of both. However, such a quantum bit is usually very unstable.
As such, the researchers decided to calculate how the resonators, diamonds and nitrogen atoms could be assembled to create an error resistant two dimensional quantum system, a so called 'topologically protected quantum computer'.
According to the calculations, about 4.5billion such quantum systems would be sufficient to implement the algorithm Shor-2048, which is able to calculate prime factors of a 2048bit number.
"Our approach has the big advantage that we know how to make the elements smaller," said Michael Trupke, also of Vienna's TU Wien. "This architecture has great potential for miniaturisation and mass production. There are still many obstacles to overcome, but connecting nitrogen spins in solid materials opens up a path that could finally lead to a functioning quantum computer."
Scientists from Japan's National Institute of Informatics and NTT's Basic Research Labs were also involved in the research.
