Simulations Show Quantum Error Not As Bad As Believed 44
aarondubrow writes "Because quantum systems become unstable quickly, their error threshold is an important factor. How many bits can 'break' before the system stops working? An international team of researchers used the supercomputers at the Texas Advanced Computing Center to simulate the error threshold of a topological quantum system and found a much higher threshold than had previously been reported."
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This is about a rather specialized type of quantum computer. Or more realistically, a proposed idea for a quantum computer.
One of the problems for quantum computing is the fragility of the quantum states that could be used. Even a tiny disturbance can cause the thing to screw up in a manner called decohering. So, there has been a push to find possible quantum computing elements that are extremely well insulated from the outside world, or that will tolerate a lot of disturbance without decohering.
Certain quantum states of quasi-particles called anyons (no joke. That's what they are called) in 2 dimensions are thought to be extremely stable.
Recently, there have been observations of states similar to these in surfaces of materials called topological insulators. They haven't conclusively shown that the right sort of states (called nonabelian) exist yet.
But, even if these so called "topologically protected" quantum states of the right sort exist, you still need an algorithm for how to compute with them.
What the Texas Advanced Computing Center team did was simulate a proposed algorithm called topological color coding for a specific case. When they did this, they found that it can withstand 10% of the underlying quantum bits screwing up.
So, it's a simulation of a proposed set of rules for computing with a proposed (but not yet demonstrated) set of quantum bits, using special quantum particles (that are composed of more than one normal particles bound together) that have not yet been shown to exist.
Although this is a very interesting area, it's a simulation of a vaporware program to run on a vaporware computer that is based on vaporware physics.
So, to say the least it's a ways off. But for solid state physics geeks it's a very hot topic of research.
Obligatory non-goatse links with useful info:
http://en.wikipedia.org/wiki/Topological_quantum_computer [wikipedia.org]
Original paper abstract: http://arxiv.org/abs/0910.0573 [arxiv.org] with links to full paper.
This work was done by the computational physics group at Texas A&M: http://comp-phys.tamu.edu/ [tamu.edu] among others.