Re: interesting article on quantum cryptography

"Antony Clements" <antony.clements@xxxxxxxxxxxxxxx> writes:

an interesting article here
http://www.networkworld.com/community/?q=node/8334&nwwpkg=alphadoggs says
that university researchers at harvard have created a working quantum
cryptographic matrix. now my question is this. since according to the
article quantum cryptography works with photons, and many of todays
encryption schemes use XOR, how would a quantum cryptographic scheme work
with such a function. except maybe to comparethe intensity of one photon
with the intensity of another and the result being the difference in their
respective inensities. any thoughts?

No. YOu need a non-linear device which for example passes one photon when
the second has the same polarization and not if it does not. Carrying out
logical operations on phontons is hard. That is why the optical qubits tend
to be converted to atomic qubits first.


.