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Quantum Physics

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Title: Centura Web Developer Author: Teknikk Last modified by: UiA Created Date: 7/17/1995 3:30:56 PM Document presentation format: Skjermfremvisning (4:3) – PowerPoint PPT presentation

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Title: Quantum Physics


1
Quantum Physics
2
Quantum PhysicsPhysics - Overview
Classical Physics
Macrocosmos (universe)
Daily life
Quantum Physics
Microcosmos (atom)
3
Quantum PhysicsWhat is Quantum Physics?
In physics, a quantum is the minimum of any
physical entity involved in an interaction. Fundam
ental physical property may be quantized.
Quantum Physics is a branch of physics providing
a mathematical description of microcosmos (atoms,
elementary particles, )
Microcosmos (atom)
4
Quantum PhysicsMicrocosmos
99.999999999999 of the atom is empty space
1000distance earth/sun
Atom Diameter 1 km
5
Quantum PhysicsMicrocosmos in our daily life
6
Quantum PhysicsMicrocosmos in our daily life -
FutureQuantum Computer
Quantum Computer
A quantum computer is a device for computation
that makes direct use of quantum physical
phenomena, such as superposition and
entanglement to perform operations on
data. Quantum computers are different from
traditional computers based on transistors. The
basic principle behind quantum computation is
that quantum properties can be used to represent
data and perform operations on these
data. Experiments have been carried out where
quantum computational operations were executed on
number of qubits (quantum bits).
7
Quantum PhysicsMicrocosmos in our daily life -
FutureQuantum Cryptograhpy
Cryptography
Cryptography is the practice and study of hiding
information. Modern crypthography intersects the
disciplines of mathematics, computer science and
electrical engineering. Quantum cryptography
describes the use of quantum physics
effects. Well-known examples of quantum
cryptography are the use of quantum
communication to securely exchange a key (quantum
key distribution). The advantage of quantum
cryptography lies in the fact that it allows the
completions of various cryptographic tasks that
er proven to be impossible using only classical
communications. In particular, quantum physics
guarantees that measuring quantum data disturbs
the data, this can be used to detect an
adversarys interference with a message.
8
Quantum PhysicsMicrocosmos in our daily life -
FutureQuantum secured bank transfer
Quantum secured bank transfer
9
Quantum PhysicsPhysics - History
. . . . . . .
2000
Quantum physics
Theory of relativity
1900
Microcosmos
Electromagnetism Thermophysics Planetary
motion Mechanics
.
10
Quantum PhysicsPlancks law of blackbody
radiation
Quantum of Energy
11
Quantum PhysicsPhotoelectric Effect
Light cannot be explained purely as a wave
phenomenon
12
Quantum PhysicsCompton scattering
Light cannot be explained purely as a wave
phenomenon
13
Quantum PhysicsDouble Slit Experiment
14
Quantum PhysicsMach-Zhender interferometer
6
4-6
0.25
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Out2
S2
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2-4
Out1
4
0.25
5
R2
0.5
4-5
S2
S1
3-5
0.5
0.25
5
1-3
S2
2
3
0.25
6
3-6
S1
Out1 3-5 4-5 0.25 0.25 0.5 Out2 3-6
4-6 0.25 0.25 0.5
Classical physics
R1
1
Out1 1 Out2 0
Quantum physics
In1
15
Quantum PhysicsEntanglement
Quantum entanglement is a physical resource (in a
way like energy) associated with the nonclassical
correlations that are possible between separated
quantum systems. A pair of quantum systems in an
entangled state can be used as a quantum
information channel to perform computational and
cryptographic tasks that are impossible for
classical systems.
16
Quantum Physicsx-ray
17
Quantum PhysicsStrange Questions
An apple is laying on a table. You measure the
position of the apple on the table. Question Whe
re was the apple just before your measurement?
Question Is it possible for a person to be at
two different places at the same
time?
Question Is it possible for two persons to
interact without any kind of communication?
18
Quantum PhysicsUnderstanding
The mankind has all time been thinking of beeing
in the centre of the world, the earth, the
planetary system, Milky Way,
How can we imagine we are seeing almost the whole
world, we are only seeing a little part of the
electromagnetic spectrum.
In microcosmos we have to learn again almost
everything, we almost have no models / pictures /
conceptions, common sense,
19
Quantum PhysicsRelativity - Addition of
velocities
Classic
Relativity
The velocity of the person relative to the earth
The velocity of the person relative to the train
The velocity of the train relative to the earth
20
Quantum PhysicsGPS - Relativity
Because of the high speed, the time moves more
slowly in the satellites. Because we are
closer to the center of the earth, the time moves
more slowly on the earth. The last effect is
greater, therefore the time goes more slowly on
the earth than in the satellite.
We have to use Einsteins theory of relativity to
adjust the time. If not, the GPS would give a
result several kilometers out of position.
21
Quantum PhysicsStrange situations in microcosmos
A measurement of a system cause a change of the
state of the system
Measuring the door makes the door smaller
A system can be in a superposition of different
states at the same time
Going through two doors at the same time
Changing spin of one of the two particles change
spin of the other though no communication
Two different systems far away from each
other can affect each other momentarily though no
communication
22
Quantum PhysicsClassical Physics ? Quantum
PhysicsStrange situations in daily lifethat
happens in micro cosmos 1/2
Classical Physics
Quantum Physics
You have parked your car.
If you know your car is parked (zero
velocity), its impossible to find it, it can be
anywhere.
23
Quantum PhysicsClassical Physics ? Quantum
PhysicsStrange situations in daily lifethat
happens in micro cosmos 2/2
Classical Physics
Quantum Physics
. . . . . . .
The laser changes the speed of the car. Its the
laser control that gives the car its speed.
Always different colors of clothes though they
dont communicate.
The cat is both dead and alive until something
controls it.
The measuring changes the high of the car so it
cannot pass the tunnel.
24
Quantum PhysicsQuotation
Niels Bohr If you are not confused by quantum
physics then you havent really understood it.
Richard Feynman I think I can safely say that
nobody understands quantum physics.
J.BHaldane The universe is not only more
strange than we suppose, but more strange that we
are able to suppose.
Daniel Greenberger Einstein said that if quantum
physics were correct, then the world would be
crazy. Einstein was right, the world is crazy.
William D. Phillips Entanglements, along with
the superposition states, is the strangest thing
about quantum physics.
Davied Bohm The most fundamental theory now
available is probabilistic in form, not
deterministic.
25
KvantefysikkInnføring
Fysikk
Matematikk
0 1 2 3 ?0 ?1
26
Quantum PhysicsStatistics - Discrete
Variables - Continuous Variables
Discrete Variables
Continuous Variables
Probability Probability density
Total probability
Expectation value
Variance
Standard deviation
27
Kvantefysikk
Kvantefysikk Størrelser som inngår i beskrivelse
av materien og dens vekselvirkning kan bare
anta bestemte, kvantiserte, verdier og ikke
forandre seg kontinuerlig fra en verdi til en
annen.
1900 Plancks strålingslov En energimengde E hf
svarende til hver frekvens f. 1905 Einstein
fotoelektrisk effekt Lys som fotoner eller
energikvanter med energi E hf h Plancks
konstant 6.626 ?10-34 Js.
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