文档介绍：puting
with Molecules
By taking advantage of nuclear
ic resonance, scientists can
coax the molecules in some
ordinary liquids to serve
as an extraordinary type
puter
by Neil Gershenfeld and Isaac L. Chuang
actoring a number with 400 dig-
its—a numerical feat needed to
Fbreak some security codes—
would take even the fastest -
puter in existence billions of years. But
a newly conceived type puter,
one that exploits quantum-mechanical
interactions, plete the task in
a year or so, thereby defeating many of
the most sophisticated encryption
schemes in use. Sensitive data are safe
for the time being, because no one has
been able to build a practical quantum The advantage of put- probabilities for all the possible states
computer. But researchers have now ers arises from the way they encode a of the quantum machine—a number that
demonstrated the feasibility of this ap- bit, the fundamental unit of informa- exceeds the capacity of the largest con-
proach. Such puter would look tion. The state of a bit in a classical dig- puter. A -
nothing like the machine that sits on puter is specified by one number, puter promises to be immensely power-
your desk; surprisingly, it might resem- 0 or 1. An n-bit binary word in a typical ful because it can be in multiple states at
ble the cup of coffee at its side. computer is accordingly described by a once—a phenomeno