Boffins build quantum bridge out of diamonds

Chinas-sky-bridgeBoffins have built a quantum bridge out of diamonds.

Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge by forcefully embedding two silicon atoms in a diamond matrix.

Sandia researcher Ryan Camacho said it was possible that the first useful quantum computer may be a  connected cluster of small ones.

Distributing quantum information on a bridge, or network, could also enable novel forms of quantum sensing, since quantum correlations allow all the atoms in the network to behave as though they were one single atom.

The joint work with Harvard University used a focused ion beam implanter at Sandia’s Ion Beam Laboratory designed for blasting single ions into precise locations on a diamond substrate.

According to Science magazine, Sandia researchers Ed Bielejec, Jose Pacheco and Daniel Perry used implantation to replace one carbon atom of the diamond with the larger silicon atom, which crowds out the two carbon atoms on either side of the silicon atom and forces them to escape.

Though the silicon atoms are embedded in a solid, they behave as though floating in a gas, and their electrons’ response to quantum stimuli are not clouded by unwanted interactions anything else.

Camacho said: “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.”

Once the silicon atoms settle in the diamond substrate, laser-generated photons bump silicon electrons into their next higher atomic energy state. When the electrons return to the lower energy state, because all things seek the lowest possible energy level, they spit out quantised photons that carry information through their frequency, intensity and the polarisation of their wave.

Sandia researcher John Abraham and other Sandia researchers developed 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.

Apparently no cats needed to be harmed in the experiments.