Sandia researchers have demonstrated for the very first time ever, how you can create a quantum bridge to interlink quantum computer on a single chip. This was performed by forecfully embedding two silicon atoms in what would be a diamond matrix.
“People have already built small quantum computers,” says Sandia researcher Ryan Camacho. “Maybe the first useful one won’t be a single giant quantum computer but a connected cluster of small ones.”
To distribute quantum information on a bridge (or network), could also enable novel forms of quantum sensing. This is so, as quantum correlations enable atoms within this network to behave as they were a single atom.
Below, you can see a stylized illustration of such a quantum bridge. It shows an array of purple holes, etched in diamond with a two silicon atoms (what would be the yellow), placed between holes.
This is a joint work with Harvard University, and it used a focused ion beam implanter at Sandia’s Ion Beam Lab which was designed for blasting single ions into specific locations on a diamond substrate.
Ed Bielejec, Jose Pacheco and Daniel Perry, all of whom Sandia researchers, used implantation to replace one carbon atom of the diamond with the larger silicon atom. This enables the two carbon atoms on either side of the silicon atom to “feel” crowded enough so they could flee. Consequently, this allows the silicon atom to be a sort of “large landowner”, plus behave buffered against stray electrical currents by the neighboring vacancies that are non-conducting.
Hence, the silicon atoms behave as though are floating in a gas, aside they are embedded in a solid. Their electrons’ response to quantum stimuli are not under the shadow of not wanted interactions with foreign matter.
“What we’ve done is implant the silicon atoms exactly where we want them,” said Camacho. “We can create thousands of implanted locations, which all yield working quantum devices, because we plant the atoms well below the surface of the substrate and anneal them in place. 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.”
Laser-generated photons can bump silicon electrons into their next higher atomic energy state, once the silicon atoms are situated in the diamond substrate, so it’s really like diamonds are not forever. As the electrons are to return to a lower energy state (as all things seek lower energy levels), they spit out quantized photons which has the ability to carry on information with their frequency, intensity and through polarization of their wave.
“Harvard researchers performed that experiment, as well as the optical and quantum measurements,” said Camacho. “We did the novel device fabrication and came up with a clever way to count exactly how many ions are implanted into the diamond substrate.”
Sandia researcher John Abraham and other Sandia researchers also worked on special detectors — metal films atop the diamond substrate — that showed the ion beam implants were successful by measuring the ionization signal produced by single ions.
The work was supported by Sandia’s Laboratory Directed Research and Development program. Some work was performed at the Center for Integrated Nanotechnologies (CINT), a Department of Energy Office of Science User Facility operated by Los Alamos and Sandia National laboratories.
Contacts and sources: Sandia National Laboratories