# Quantum Cryptography

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08-Jun-2015Category

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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.