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QUANTUM QUANTUM CRYPTOGRAPHY CRYPTOGRAPHY Jennifer Nalley Jennifer Nalley 2008 2008
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08-Jun-2015
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This is a PowerPoint about one of the possible applications of quantum entanglement. I made this PP for a tech writing class.

### Transcript of Quantum Cryptography

• 1. QUANTUM CRYPTOGRAPHY Jennifer Nalley 2008

2. Cryptography

• (krypts)
• hidden
• +
• (grpho)
• write
• =
• Hidden Writing

3. Classic Cryptography

• Encrypt(plaintext -> cipher text)
• Transmit cipher text
• Decrypt ( cipher text -> plaintext)
• Secure for as long as the algorithm is

4. Cryptography is an old art

• A Transposition Cipher
• (700 BC)

5. Modern Cryptography

• Early computer cryptosystems used mathematical complexities to provide security
• Multiplying two huge prime numbers is quick, but factoring such a composite number is computationally intensive.(even for a computer)
• As computer technologies advance, mathematical complexity may not be a guarantee for security .(Someone in Derrick Hall could crack today's best code, and rob us all)

6. Quantum Cryptography is SuperiorBecause it is UNBREAKABLE

• Quantum Cryptography
• obtains its fundamental
• security from the fact
• that each Q-bit is
• carried by a single
• photon, andeach
• photon will be altered
• as soon asit is read.
• (a side effect of quantum behavior)
• This makesitimpossibleto intercept message without being detected .

7. Heisenberg Uncertainty Principle and Quantum Mechanics

• TERMINOLOGY:Observable-some measurable feature of a quantum particle. Examples of observables include: a particles position (where the particle is), momentum (classically equal to mass x velocity)
• In the quantum world, nothing is certain:MeasurementCAN NOTbe made without perturbation. Heisenberg uncertainty principle does not allow for conjugate values of precision(for any two observables).Specifically, the act of obtaining a measurement of one observable, limits the degree of certainty on any second measurement.(Et ).
• Sometimes two particles can become ENTANGLED. When this occurs, act of measuring an observable on one particle..seems to instantaneously determine the orientation of the second. This is strange, but utilizable.
• Consider polarized light

8. Polarized Light

• When measuring the polarization of a photon, the choice of what direction to measure affects all subsequent measurements.
• If a photon passes through a vertical filter
• it will have the vertical orientation regardless of its initialdirection of polarization .

9. In all

• Taking into account the use ofpolarizedlight.recall
• that:
• Quantum Cryptography
• obtains its fundamental
• security from the fact
• that each Q-bit is
• carried by asingle
• photon, and each
• photon will be altered
• as soon asit is read.
• We have an indeterminate system, one that carries information.
• An act done at will to one part of the system determines the outcome of the other.
• We have an ideal set-up for securing information .

10. And.to go into further detail

• Would require some mathematics some of you may not enjoy
• .not to mention the time issue.
• Had I thought ahead, I would have covered something like, The physics of roller-skating.