Quantum computers are a proposed series of supercomputers that use light instead of electricity to process tremendous amounts of data and solve complex problems.
Although this innovation could be years away, a team of engineers led by Stanford University electrical engineering Professor Jelena Vuckovic are exploring specialized materials to bring this concept closer to becoming a reality.
Quantum computers work by isolating spinning electrons inside a new type of semiconductor material. A laser then strikes the electron revealing which way it’s spinning by producing one or more particles of light, which essentially replaces the ones and zeros of traditional computing.
“With electronics you have zeros and ones,” said Marina Radulaski, a postdoctoral fellow in Vukovic’s lab, in a statement. “But when the laser hits the electron in a quantum system, it creates many possible spin states, and that greater range of possibilities forms the basis for more complex computing.”
The scientists tested three different approaches using semiconductor crystals in order to trap a single, isolated electron.
First, the team developed a structure called a quantum dot. It’s comprised of a small amount of indium arsenide inside a crystal of gallium arsenide. Both materials have atomic properties known for trapping spinning electrons.
Essentially, the experiment entailed controlling the input and output of light within the structure. The researchers were able to force the dot to emit two photons rather than one by sending more laser power to it.
Two other trials focused on altering a single crystal to trap light in color centers located in diamonds
One process involved replacing the carbon atoms residing the crystalline lattice of a diamond with silicon atoms. This yielded a color center that effectively trapped electrons in the lattice.
Another experiment used a hard, transparent crystal known as silicon carbide. The scientists removed specific silicon atoms out of the lattice to create efficient color centers while also molding nanowire structures around these centers to enhance the extraction of photons.
“We think we’ve demonstrated a practical approach to making a quantum chip,” elaborated Radulaski.
The team isn’t sure which material or method is the best one approach so they will continue to experiment.
Still, developing these pint-sized components could be key to creating these future systems, but the challenge is to find the best materials that can be super-cooled to near absolute zero.
