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Quantum Mechanics
I don't like it, and I'm sorry I ever had anything
to do with it. -- Erwin Schrodinger talking
about Quantum Physics
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Quantum Mechanics
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Photoelectric effect
Wave particle duality
Characteristic energy
Quantum numbers
Electron spin
Electron tunneling
Uncertainty principle
Quantum entanglement
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Quantum Numbers
There are four numbers that come into the theory of
electron clouds as waves called quantum numbers.
The first quantum number, n, is the principle energy
level. This is the 1 in 1s2. It can have the values 1,
2, 3, …
The second quantum number, l, is the sublevel. The
nth principle energy level has n sublevels. We refer
to these sublevels by letters: s, p, d, f, g, h, i, j, k, …
Sometimes numbers are used too: 0, 1, 2, 3, …(n-1)
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Quantum Numbers
The third quantum number, ml, is the orbital. Every
sublevel has one or more orbitals. The s sublevel
has 1 orbital, the p sublevel has 3 orbitals, the d
sublevel has 5 orbitals, etc. These orbital can be
indicated by the number ml = l, l-1, …0, -1, … -l
The fourth quantum number, ms, is the spin of the
electron. Electrons can be either spin up or spin
down. ms can be either +½ or -½
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Electron Spin
In order for two electrons to occupy the same
orbital they must have opposite spin.
Electrons can either have spin +½ or –½
Spintronics: This is a new type of electronics which
is based on the spin of the electrons.
It is possible to filter electrons which have different
spins using very thin magnetic films.
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Electron Tunneling
The electron has some probability of
penetrating a barrier which it does not have
enough energy to overcome. For example an
electron can pass through a very thin
insulating layer resulting in a tunneling
current.
http://www.quantum-physics.polytechnique.fr/en/index.html
http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/barr.html#c1
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Quantum Electrodynamics
QED
Richard Feynman won his Nobel prize for his work
in this field.
In QED electric fields are better represented
quantum mechanically as the exchange of virtual
photons with subatomic particles such as protons
and electrons.
http://www.vega.org.uk/series/lectures/feynman/
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Insert Quantum Mechanics Cartoon Here
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Quantum Information and Computers
Qubits – consist of logical storage that can be
0, 1 or indeterminant between 0 and 1
Writing data: Excite an electron from E0 to E1
Reading data: Excite with energy E2-E1and
analyze the photons given off
Quantum entanglement
Quantum error correction codes
The answer occurs as a superposition of all
possible answers
Quantum algorithms
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Quantum Information and Computers
Data encryption is the basis for electronic transactions. It relies on
the factoring of large numbers which is difficult for ordinary
computers to accomplish. Quantum computers would be able to
compute the factors in seconds.
Quantum computers would also be extremely efficient search
engines
A 40 qubit computer could complete in 100 steps a calculation that
would take a classical computer with a trillion bits several years to
compute
A 100 qubit computer would be more powerful than all the
computers in the world linked together
Quantum encryption would result in an unbreakable code
Quantum computers have been attempted using NMR
Shor’s Algorithm for factoring numbers has been demonstrated on
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Quantum Computers
DWave Systems http://www.dwavesys.com/
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Quantum Entanglement
This forms the basis for quantum computing.
By a suitable choice of operations carried out on one system
a second system can be constrained to a particular set of
states.
If two particles become entangled then information can be
transmitted between them.
When you read the state of one system you end up erasing
the state of the other system.
You can not make multiple copies of quantum information.
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Quantum Mechanics
Photoelectric effect
 Characteristic energy
 Quantum numbers
 Wave particle duality
 Electron spin
 Electron tunneling
 Uncertainty principle
 Quantum entanglement
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The Uncertainty Principle
The more precisely the position is determined the
less precisely the momentum is known.
Δx Δp ≥ h/2π where x is location and p is
momentum.
We cannot predict exactly what will happen but only
assign probabilities.
http://hyperphysics.phy-astr.gsu.edu/hbase/uncer.html
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http://newsbureau.upmc.com/TX/Nanotubes04.htm
http://www.news.utoronto.ca/bin6/050110-832.asp
http://www.vega.org.uk/series/lectures/feynman/
http://informationweek.com/story/showArticle.jhtml?articleID=59300089
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