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Quantum Computation article
David P. DiVincenzo from the IBM Research Division has written an article
in the 13th October issue of SCIENCE magazine (vol. 270, pg. 255-261)
entitled "Quantum Computation". The article is nicely divide into
- Building blocks of quantum logic
- Quantum circuits
- Peter Shor's prime factorization
- The decoherence problem
From the outlook section "It is evident from this survey of the current
state of the art in quantum experimental physics that the construction of
quantum computers is presently in the most rudimentary stage, and that to
even think about a procedure like Shor factorization, which might require
millions of operations on thousands of qubits, might be absurdly premature."
If that is the good news for Cypherpunks, then the great news is the
". . even a few bits of quantum computation will be very useful in
performing so-called Bell measurements, which could be used to implement
quantum teleportation, in which an unknown quantum state can be
trasmitted to a remote location. At perhaps the 10-qubit level, a
quantum computer becomes capable of performing Schumacher's quantum
coding, which would be of interest in the implementation of efficient
quantum cryptography. And at perhaps the 100-qubit level, a quantum
computer becomes an efficient repeater for a noisy (that is partially
decohered) quantum cryptographic link."
It looks like the advantages of quantum computing accrue to Alice and
Bob, long before it becomes useful to Eve and Mallet.
A must read for aficianados of "alternative computing".
Here are some URLs from the references
(Quantum Information Page, Center for Advanced Accelerators)
(Quantum Computation and Cryptography page, Clarendon Laboratory, Oxford
C. J. Leonard ( / "DNA is groovy"
\ / - Watson & Crick
<[email protected]> / \ <-- major groove
Finger for public key \ )
Strong-arm for secret key / <-- minor groove
Thumb-screws for pass-phrase / )