A new technique for fabricating quantum bits in silicon carbide wafers could provide a scalable platform for future quantum computers. The quantum bits, to the surprise of the researchers, can even be fabricated from a commercial chip built for conventional computing.
The recipe was surprisingly simple: Buy a commercially available wafer of silicon carbide (a temperature-robust semiconductor used in electric vehicles, LED lights, solar cells, and 5G gear) and shoot an electron beam at it. The beam creates a deficiency in the wafer which behaves, essentially, as a single electron spin that can be manipulated electrically, magnetically, or optically.
“It’s ironic after 50 years or so of trying to clean up semiconductors to make high-quality electronics, our plan is to put the defects back in—and use them to make a trapped atom in a semiconductor,” says David Awschalom, professor of molecular engineering at the University of Chicago.
Awschalom says his group at Chicago is one of a number that have followed up on the promise of a pioneering 2011 paper by researchers at the University of California, Santa Barbara—who first discovered that small defects in silicon carbide could be manipulated to become essentially room-temperature cages for individual electrons, whose spins can then be used as a quantum bit for possible computations and communications.
And these individual electron spins inside silicon carbide, subsequent research has established, retain their quantum information for up to a millisecond (a long time in the world of quantum computing) and can be tuned and addressed both with electrical gates and with lasers.
The technique could offer a rare medium that’s isolated enough from thermal noise to host quantum phenomena like entanglement—but not so isolated that qubits can’t be manipulated and run through a series of gates and logical operations.
“Our approach is to see if we can leverage the trillion dollars or so of American industry that’s building today’s nanoelectronics and see if we can pivot that technology,” Awschalom says.
Read more at IEEE Spectrum.
Image: Like stars in a color-enhanced snapshot of the night sky, these yellow-green dots represent sites on a silicon carbide wafer where an electron beam has knocked out one silicon atom and one carbon atom. What’s left behind is a “divacancy” pocket that harbors a single addressable electron. Researchers have found these single electron structures can be harnessed as possible quantum bits for quantum computation and communications. Courtesy of David Awschalom.