Monday, November 07, 2005

QC and Security

After the research we have done, I find the most interesting part of QC is the way it employs these theoretical ideas and applies them in such a practical way. We know from our work at the beginning of the semester about Shrodinger's Cat. This is the idea that the mere observation of an event can change its very characteristics. Quantum Cryptography employs this in a very practical manner. If a party sends a packet of information (photons in this case) to another party, the receiving party will know whether that packet of information has been observed if its characterstics have changed.
This article goes into a bit more detail.

Nature reports that on the 21st of April, Austrian scientists used quantum cryptography to transfer a US$3,500 donation to their laboratory.The article explains."Quantum cryptography uses the odd properties of quantum particles to create secure keys for encoding and decoding messages.The very act of observing these particles changes their nature, making it easy to detect any eavesdroppers.Anton Zeilinger, a quantum physicist at the University of Vienna, and his team carried out their bank transaction by applying a particularly secure technique that uses a pair of entangled photons to create the key.The properties of these photons depend on each other, even when they are separated by long distances. After entangling the pair, one is sent to the recipient. Upon arrival, both photons are measured by their respective owners. This act of measurement determines the state of the photons, and thus the state of the key.Before measurement, neither photon carries any useful information that could be stolen by a snoop. "This makes data transmission more secure," says Zeilinger."

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