Quantum Cryptography

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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.