by Unruh <unruh-spam@[EMAIL PROTECTED]
>
Apr 13, 2006 at 09:26 PM
"ergun" <ergungumus@[EMAIL PROTECTED]
> writes:
>Hi,
>I have been reading Quantum Cryptography related papers for a short
>while and I encountered some questions. Could any one of you clarify
>them for me ?
>1) Why the last bit of each block is discarded in reconciliation
>process (parity check) of BB84 algorithm?
>2) It is said that Eve can not eavesdrop without being detected because
>she can use only rectilinear filter or diagonal filter. If she chooses
>the wrong one this would change the polarization of photon and she can
>be detected. I don't have any idea about filters but is not it possible
>to make ONE filter that is both diagonal and rectilinear so that any
>kind of photon polarization can be read without changing it ?
No. Those are non-commuting observables in the language of quantum
mechanics and thus only one can be measured on any single photon. After
that measurement the other has been altered (so that there is not relation
between the value and the original value)
>3) It is said that in privacy amplification step, n-m-s blocks are
>chosen and their parity bits form the key for encryption. What does the
>values of m and s depend on?
>Thanks in advance.
