Scientists slam carbon out of diamonds to create the first quantum computing bridge

Quantum computers are a reality but unlike the first traditional computers, which were large enough to fill a room, most of today’s quantum computers are very small with one, five, or even 16 qubits at their core and getting to the point where we have a truly practical quantum computer is going to require component by component advances until, one day, we get to the point where all of the blocks "just work".

Researchers from Harvard University and Sandia Ion Beam Laboratory have just managed to make such an advance - by figuring out a way to link multiple quantum systems together within one piece of material.

Using a focused ion beam implanter, the scientists first knocked out one carbon atom from a diamond substrate and replaced it with a larger silicon atom. Once the silicon atom was in place, it effectively crowded out its neighbouring carbon atoms, leaving it buffered.

Because of this buffer, the material is useful for two reasons. First, the gap acts as an insulator from electrical currents that could be run through the diamond substrate. And second, Sandia says that the embedded silicon atoms behave as though they are suspended in a gas - even though they're in the solid diamond substrate, so "their electrons' response to quantum stimuli are not clouded by unwanted interactions with other matter."

Unlike the idea of a quantum data bus, the new quantum bridge eliminates the efficiencies of moving quantum bits individually over a distance. Instead, when laser-produced photons are pumped into the material, all of the silicon electrons are simultaneously excited into a higher atomic energy state so that, when the electrons revert to their lower energy state, they all emit groups of quantized photons that maintain 100 percent quantum integrity.

The scientists can implant thousands of these silicon atoms onto a single diamond substrate, thus creating what the scientists calla “quantum bridge”  between these multiple quantum devices.

“Before this, researchers had to search for emitter atoms among about 1,000 randomly occurring defects — that is, non-carbon atoms — in a diamond substrate of a few microns to find even one that emitted strongly enough to be useful at the single photon level,” said Sandia researcher Ryan Camacho in a news release.

If the promise of this new research holds true, it could be the key to scaling up quantum computers, which would be orders of magnitude more powerful than the computers we have now.

But more than just being faster at traditional operations, quantum computers truly shine at applications classical computers find hard. For example, a standard weakness of traditional computers is factoring large numbers, but a quantum computer using what is called Shor’s algorithm can complete such operations in mere seconds - with Google recently announcing that they had managed to use their D-Wave X2 quantum computer to process information 100 million times faster than a classical computer given the same task.

So many fields, including medicine, financial services, defense, and telecommunications, would be radically changed by the creation of multiple-quantum computer systems. Quantum technology is truly the future of computing, and this research from Harvard and Sandia brings us one step closer to realizing that future.