Bits of reality
Not just for codes and computers,
quantum information holds clues to the nature
of the physical universe
By Tom Siegfried
Ask any physicist to name the top two theories of the 20th century, and you’ll almost always get the same automatic answer: Einstein’s relativity and quantum mechanics. But lately a few 21st cen-
tury thinkers have hinted that maybe the third-place theory
should move up a notch. In the wake of the computer revolu-
tion, information theory might deserve to displace relativity
in the rankings.
A unit of quantum information, or qubit,
can be represented as a point on the
surface of a sphere. The angles formed
by the radius to that point can be used
to calculate the odds that the qubit
will become 0 or 1 when measured.
At the heart of quantum information science is a novel representation for information known as the qubit. It’s the quantum
analog of the 1s and 0s, or “bits,” processed
by ordinary computers. But a qubit is
infused with quantum magic, allowing it
be both a 1 and a 0 at the same time. This
“superposition” of identities gives quantum information extraordinary power.