The researchers say a leading qubit candidate is individual ions trapped inside a vacuum chamber and manipulated with lasers. But the team says because the connections for the electrodes needed to generate the trapping fields come at the edge of the chip, their number is limited by the chip's perimeter.
The team's approach uses new microfabrication techniques that allow more electrodes to fit onto the chip, while preserving the laser access needed.
The team's design borrows ideas from the BGA package, where the density of electrical connection is increased.
"Ions are very sensitive to stray electric fields and other noise sources, and a few microns of the wrong material in the wrong place can ruin a trap. But when we ran the BGA trap through a series of benchmarking tests, we were pleasantly surprised that it performed at least as well as all our previous traps," said team leader Nicholas Guise.
More chip space was also provided by replacing surface or edge capacitors with trench capacitors and by moving wire connections.
The team will now work to shrink the technology and to address the engineering challenges involved into creating a packaged system that would enable quantum computing.
