Scientists develop laser-beam steering system for quantum computing

Scientists have developed a laser-beam steering system which is able to aim and focus burst onto specific atoms which will provide uses within quantum computers.

The steering system, developed by collaborating researchers at Duke University and the University of Wisconsin-Madison, is thought to be similar to laser light show you might find at a planetarium, conjuring an image of a Jean-Michel Jarre gig on an atomic scale.

However the technology used is smaller, faster and aimed at the future of computing rather than lighting up random locations across the globe such as the Pyramids, to a background of nauseating trance music like Mr Jarre, 62, would do.

Quantum computers are able to solve complex and important problems if their basic elements, named qubits, remain in a special state of quantum entanglement for a long enough time for the calculations to be carried out before information is lost due to natural fluctuations.

The new steering is one of several approaches to quantum computing which use arrays of individual atoms suspended by electromagnetic forces. Pulses of laser light are used to manipulate the internal states of the atoms that represent the qubits to carry out the calculation.

However the lasers must also be focused and aimed in a perfectly accurate way, so that light meant for one atom doesn’t affect other nearby atoms.

The steering system was crucially able to focus on the exact atoms without disturbing others.  It uses tiny micromirrors – roughly twice the size of a human hair in diameter – which are able to target each atom in just 5 microseconds.  This is approximately 1,000 times faster than the most sophisticated beam steering mirrors that have been developed for optical communications switching, and certainly faster than a concert light show.

The scientists saw that the laser pulses were able to correctly manipulate the quantum properties of each target atom at these speeds, in this case a line of five rubidium-87 atoms, while avoiding any disturbance of other molecules at all times which would only be 8.7 microns away, the equivalent to one-tenth the diameter of a human hair.

“Our experiments demonstrated the crucial requirement that our micromirror system maintain the laser-beam quality necessary to manipulate the internal states of the individual atoms,” said Jungsang Kim, leader of the Duke researchers who designed the micromirror system.

The group has further plans to continue the work at the University of Wisconsin-Madison, with the ambition of developing two-qubit gates – expected to be the basic building block of quantum logic – and atoms confined in larger two-dimensional arrays.  A video to show how the technology would work with a 5×5 array can be seen here.