In Quantum computing, we work with binary digits.
or bits - which are in a state of
zero or one, represented
by an electrical charge on a capacitor,
for example.
In the future, however, we may use quantum
computing, in which quantum bits, or Qbits,
can be more than just zero or one. They can be
zero and one - at the same time.  They can be
at a preposition state, because the states
When two or more Qbits interact with each
other, their joint states can become
entangled. In an entangled, or ensemble of
Qbits, the whole system evolves in a highly
coupled fashion.
A delicate dance of waves,
leading to a massively parallel
operation.
Thus, quantum parallelism can be
used in quantum microprocessors
and leads to greatly increased
computation speed; bringing
special problems within reach of 
being solved, that would have taken classic 
computers - billions of years to solve.
Entangled superpositional states are quite
common, actually, in nature.
Yet, they are very, very hard to control.
Will we ever be able to build a large-scale
quantum computer with thousands of Qbits?
I think so.
Many physical implementations are being
pursued in laboratories around the world.
In my group at Berkeley Lab, we are working on
integration of electron spin Qbits in
diamonds and silicon.
The exponential increase of
computational power driven by the mastery
of silicon technologies that we have
enjoyed last fifty years will slow down
as scaling reaches atomic 
dimensions. Yet, 
we've just scratched the surface of
silicon, 
and now we've become curious about the quantum
mechanics of small devices and find
ways to implement quantum 
functionality
to make the largest, classic
supercomputer look an abacus.
