a new way to build quantum computers?

[James A. Donald]

     --
Steven M. Bellovin wrote:
 > http://www.tgdaily.com/content/view/33425/118/
 >
 > "Ann Arbor (MI) - University of Michigan scientists
 > have discovered a breakthrough way to utilize light in
 > cryptography. The new technique can crack even complex
 > codes in a matter of seconds. Scientists believe this
 > technique offers much advancement over current
 > solutions and could serve to foil national and
 > personal security threats if employed."...
 >
 > I'll let those who know more physics comment in
 > detail; from reading the article, it appears to lead
 > to a way to construct quantum computers.

It is another *in* *principle* design:  The computer is
programmed and supplied with data at optical
frequencies.  We cannot modulate light at that frequency
with sufficient precision and detail.  Perhaps we will
be able to soon.

As Moore's law progresses, quantum effects get
relatively larger.  Another way of stating this proposal
is to say that when we can build classical computers
with nanoscale line widths and hundred terahertz clocks,
*then* we can build quantum computers - indeed, we will
have to, as our classical computers will start acting
weirdly due to quantum effects.

Quantum computers are best done with the highest
possible frequencies and the lowest possible energies,
so become more feasible as conventional computers become
faster and more energy efficient. If we had optical
computing at optical frequencies with quantum dots
acting as the nonlinear elements, yes, quantum effects
would be quite large, making classical computers harder,
and quantum computers easier.

If we could build a quantum computer of this design, we
could build a classical computer that operated at five
hundred terahertz, and in order program and interface
with the proposed quantum computer, we are going to
*need* a classical computer that operates at five
hundred terahertz, that is to say five hundred thousand
gigahertz, that is to say five million megahertz.

It will be a while before you can buy that one at Fry's.

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