was reported in Nature, a group led by
researchers in France announced a similar feat.
“This is the beginning of the field, but
we’ve proven that this is a possible task,”
says Patrice Bertet, a quantum physicist
at the French laboratory CEA Saclay.
Bertet and his colleagues’ would-be
diamond hard drive, reported online
at arXiv.org, isn’t very useful right now.
One diamond chip stores only a single
bit of information, and for just a couple
hundred nanoseconds. What’s more,
only about one in seven attempts to
swap information succeeded. Though
the Japanese team didn’t fare any better, both experiments show that hybrids
may turn out to be more than just an idea
on a physicist’s wish list.
For all their sparkle, diamonds aren’t the
only way to bling out a superconducting
circuit with prewrapped qubits. Rubies
contain interesting chromium impurities with spins that could be the Juliet to
the Romeo that is superconducting circuits. One group of researchers wants to
use nitrogen atoms caged within buckyballs— carbon spheres that resemble
geodesic domes. Another is playing with
rare earth atoms that could be useful for
One set of blueprints calls for exotic
entities whose existence hasn’t even
been confirmed yet. Last spring, a team
led by theoretical physicist John Preskill
of Caltech extolled the benefits of tucking information inside “anyons.” These
t wo-dimensional particles are thought to
inhabit the surfaces of bizarre materials
known as topological insulators, which
behave in strange ways when it comes
to conducting electricity. In theory, an
anyon would have to be disturbed at two
points at once to lose its information,
offering the ultimate in reliable storage.
“There are other materials that seem
to have the interesting quantum properties found in diamond,” says David
Awschalom, a physicist at the University
of California, Santa Barbara.
Awschalom has taken a pragmatic
approach to quantum hard drives. He’s
This hybrid device, created when a
Japanese team glued a diamond chip
(shown) to a superconducting circuit
(hidden below), was able to pass information between its two parts.
testing materials that engineers already
know how to work with—mundane
silicon semiconductors that star in
today’s electronics. A semiconductor-superconductor hybrid would be a decidedly practical match.
Silicon carbide, used in high-power
transistors and other equipment, seems
to have the right stuff for storing quantum information. Like diamond, the
material is dotted with defects. Reporting in the Nov. 3 Nature, Awschalom’s
team controlled the spins of electrons
in these defects. Computer simulations
done by the researchers have revealed
more than a dozen other promising
materials, including magnesium oxide,
zinc oxide and aluminum oxide.
Hybrids with hardware made of semiconductors or diamond would offer an
added bonus: They would have a built-in
modem that could allow future quantum
computers to broadcast the information
they store. Physicists are keen to eventually construct a quantum network
spanning great distances.
“You might like to make a quantum
Internet some day,” says Yale’s Robert
Schoelkopf, a quantum physicist and
superconducting qubit pioneer.
Superconducting circuits can’t talk to
the particles of light that carry informa-
tion on fiber-optic cables. But electrons
in diamonds and silicon carbide can,
while still being relatively easy to work
with. Modems made from these materi-
als could extend the reach of quantum
information from different spots on the
same superconducting chip to different
places on the globe.
s For more about the spooky physics
behind quantum computers, check out
Science News’ special quantum issue:
March 10, 2012 | SCIENCE NEWS | 29