Researchers at the Max Planck institute for Quantum Optics in Garching, Germany, have created a first of its kind: A virtual reality simulator that does not actually create simulations in VR-space. Instead, they exist in physical dimensions, just not exactly normal matter.

An object made out of two conjoined atoms, and suspended in a vacuum.

This physical construct might not seemingly have anything in common with VR, but it is in fact a quantum simulator. Its entire purpose is to simulate the forces normal VRs which are wholly computer rendered, simply cannot as we do not fully understand the equations, nor possess the processing power to do so.

Tobias Schätz and his collaborators used laser light to vary the electrical repulsion of the ions in order to simulate the magnetic interaction of atoms. Essentially, the machine could use one force of nature to simulate the other.

"This is pretty important that they've been able to demonstrate the principle," said John Chiaverini of the Los Alamos National Laboratory in New Mexico.

"I feel the experiment is an important initial step in the emerging field of quantum simulation," said David Wineland of the National Institute of Standards and Technology in Boulder, Colo., whose group in 2002 pioneered a more limited quantum simulation technique by trapping single ions. The new experiment "demonstrates important tools that can potentially be implemented on much larger systems whose simulations are intractable by classical means," he says.

It was the late physicist Richard Feynman who pointed out in 1982 that ordinary computers can't possibly simulate true quantum behavior of a large number of particles. That's because of the phenomenon of superposition, which allows a particle to be in two states at the same time. For example, the spin of an atom - the quantum version of a bar magnet - can point simultaneously up and down.

Feynman reasoned that to simulate, say, the spin states of an object made of two atoms, a computer has to keep track of four possible combinations of spins: up-up, up-down, down-up, and down-down. For three atoms, eight possibilities exist, and the number keeps growing exponentially. For n atoms, the number is 2n, which gets very large very quickly. "This 2n - that's what kills classical computers," said Schätz.

Chiaverini said even state-of-the-art supercomputers quickly get overwhelmed with all the calculations required to predict how all those spin states will evolve in time. "You run out of steam at about 40 spins," he said.

References

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