Wednesday, May 2, 2012

Order of magnitude advance in QC: "The ion-crystal used is poised to create one of the most powerful computers ever developed,"

Previous efforts at realizing a quantum simulator have had problems with decoherence and other systemic errors past 10~ qubits. This advance is roughly 10 ten times more than the previous record. Quantum simulators are used to model systems such that parameters that could not be physically varied in the original system can be with the modeled analogue parameters. That is the computation that they are referring to when they say a computer the size of the universe would be needed to perform the calculations.

For instance, the quantum behaviour of these hundred so spin qubits mimicks the behaviour found in numerous mesoscale systems, particularly lattices. In those systems, varying the lattice length and / or other parameters describing the system is often physically impossible or otherwise restrictively difficult, and completely impossible to simulate with a computer. By creating an analogue, pseudo-variations can be performed that give insight into the underlying structure and lead to a better understanding of the original lattice.

From the arXiv paper below the news story: a tunable parameter that mimicks various physical couplings.
That is, by adjusting the single experimental parameter μR we can mimic a continuum of physical couplings including important special cases: a = 0 is infinite range, a = 1 is monopole-monopole (Coulomb-like), a = 2 is monopole-dipole and a = 3 is dipole-dipole. Note that a = 0 results in the so-called Jˆz interaction that gives rise to spin-
squeezing and is used in quantum logic gates (see Supple-
mentary Information) [27]. In addition, tuning μR also permits
access to both antiferromagnetic (AFM, μR > ω1 ) and ferro-
magnetic (FM, ω2 μR < ω1 ) couplings [13].
http://sydney.edu.au/news/84.html?newsstoryid=9081
"The system we have developed has the potential to perform calculations that would require a supercomputer larger than the size of the known universe - and it does it all in a diameter of less than a millimetre," said Dr Biercuk.
"The projected performance of this new experimental quantum simulator eclipses the current maximum capacity of any known computer by an astonishing 10 to the power of 80. That is 1 followed by 80 zeros, in other words 80 orders of magnitude, a truly mind-boggling scale."
The work smashes previous records in terms of the number of elements working together in a quantum simulator, and therefore the complexity of the problems that can be addressed
Most recent paper from author:
http://arxiv.org/abs/1204.5789

Engineered 2D Ising interactions on a trapped-ion quantum simulator with hundreds of spins