Re: interesting article on quantum cryptography

Antony Clements wrote:
i know you dont need a quantum computer to do quantum cryptography, but if
the device has 4 selectable polarization states then every photon will have
a electrical state of one of those four settings. i say electrical state
because for something to be polarized it means to be magnetic in some way or
another, and magnetism co-exists with electricity.

There are some misconceptions there. The way that quantum coherence
works *requires* that the coherent photons *cannot* have definite
polarization states associated with them individually, until a
measurement is actually made. There are generally only two possible
outcomes of a polarization measurement, not four. (There are
different kinds of polarization: linear, circular, elliptical, but
they can be expressed in terms of each other.) Polarization as
applied to photons does not mean having acquired some amount of
magnetism; it means aligning their mode of oscillation into set
patterns.

i can see no way for a pure software implementation of a quantum
cryptoraphic matrix since software can not produce photons. you can however
have software that controls the photon emitter, just as you can have a
hardware arrangement that does the same thing.

It is certainly possible for software to simulate quantum behavior.
However, the point of quantum cryptography is to rely on the laws
of physics to obtain an absolute guarantee of security.
.

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