Quantum PhysicsQuantum Physics

Quantum PhysicsPhysics - OverviewQuantum PhysicsPhysics - Overview

Macrocosmos (universe)

Microcosmos (atom)

Daily life

Classical Physics

Quantum Physics

Quantum PhysicsWhat is Quantum Physics?Quantum PhysicsWhat is Quantum Physics?

Microcosmos (atom)

Quantum Physics is a branch of physicsproviding a mathematical description of microcosmos (atoms, elementary particles, …)

In physics, a quantum is the minimum of any physical entity involved in an interaction.Fundamental physical property may be ’quantized’.

Quantum PhysicsMicrocosmosQuantum PhysicsMicrocosmos

99.999999999999 %of the atom is empty space

AtomDiameter = 1 km

1000*distanceearth/sun

Quantum PhysicsMicrocosmos in our daily lifeQuantum PhysicsMicrocosmos in our daily life

Quantum PhysicsMicrocosmos in our daily life - FutureQuantum Computer

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 dataand perform operations on these data.

Experiments have been carried out where quantum computational operations were executed on number of qubits (quantum bits).

Quantum PhysicsMicrocosmos in our daily life - FutureQuantum Cryptograhpy

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 communicationto 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 adversary’s interference with a message.

Quantum PhysicsMicrocosmos in our daily life - FutureQuantum secured bank transfer

Quantum PhysicsMicrocosmos in our daily life - FutureQuantum secured bank transfer

Quantum secured bank transfer

Quantum PhysicsPhysics - HistoryQuantum PhysicsPhysics - History

ElectromagnetismThermophysicsPlanetary motionMechanics

1900 Microcosmos

Theory of relativity

Quantum physics

2000

.

.

.

.

.

.

.

.

Quantum PhysicsPlanck’s law of blackbody radiationQuantum PhysicsPlanck’s law of blackbody radiation

1e

1

c

hν2)T,I(ν

kT

hν2

3

Quantum of Energy

Quantum PhysicsPhotoelectric EffectQuantum PhysicsPhotoelectric Effect

Light cannot be explained purely as a wave phenomenon

Quantum PhysicsCompton scatteringQuantum PhysicsCompton scattering

Light cannot be explained purely as a wave phenomenon

Quantum PhysicsDouble Slit ExperimentQuantum PhysicsDouble Slit Experiment

Quantum PhysicsMach-Zhender interferometerQuantum PhysicsMach-Zhender interferometer

1

2

1

2 1

2

1

S1

S2

R1

R2

2

In1

Out1

Out2

1

2 3

45

6

S1

S2

S2

1-3

2-4

4-6

4-5

3-5

3-6

0.5

Out1 : 3-5 + 4-5 = 0.25 + 0.25 = 0.5Out2 : 3-6 + 4-6 = 0.25 + 0.25 = 0.5

0.25

0.25

0.25

0.25

0.5

6

5

5

6

Classical physics

Out1 : 1Out2 : 0

Quantum physics

Quantum PhysicsEntanglementQuantum 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.

Quantum Physicsx-rayQuantum Physicsx-ray

Quantum PhysicsStrange QuestionsQuantum PhysicsStrange Questions

An apple is laying on a table.You measure the position of the apple on the table.

Question:Where 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 interactwithout any kind of communication?

Quantum PhysicsUnderstandingQuantum 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 imaginewe are seeing almost the whole world,we are only seeing a little part ofthe electromagnetic spectrum.

In microcosmos we have to learn again almost everything,we almost have no models / pictures / conceptions, common sense, …

Quantum PhysicsRelativity - Addition of velocitiesQuantum PhysicsRelativity - Addition of velocities

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km

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The velocity of the personrelative to the earth

The velocity of the personrelative to the train

The velocity of the trainrelative to the earth

Classic:

Relativity:

Quantum PhysicsGPS - RelativityQuantum PhysicsGPS - Relativity

Because of the high speed,the time moves more slowlyin the satellites.

Because we are closerto the center of the earth,the time moves more slowlyon the earth.

The last effect is greater,therefore the time goes more slowlyon the earth than in the satellite.

We have to use Einstein’s theory of relativityto adjust the time.If not, the GPS would give a resultseveral kilometers out of position.

Quantum PhysicsStrange situations in microcosmosQuantum PhysicsStrange situations in microcosmos

A measurement of a system cause a change of the state of the system

A system can be in a superposition of different states at the same time

Two different systems far away from each othercan affect each other momentarilythough no communication

Measuring the doormakes the door smaller

Going through two doorsat the same time

Changing spinof one of the two particleschange spin of the otherthough no communication

Quantum PhysicsClassical Physics Quantum PhysicsStrange situations in daily lifethat happens in micro cosmos [1/2]

Quantum PhysicsClassical Physics Quantum PhysicsStrange situations in daily lifethat happens in micro cosmos [1/2]

ClassicalPhysics

QuantumPhysics

You have parked your car.

If you know your car is parked (zero velocity),it’s impossible to find it, it can be anywhere.

Quantum PhysicsClassical Physics Quantum PhysicsStrange situations in daily lifethat happens in micro cosmos [2/2]

Quantum PhysicsClassical Physics Quantum PhysicsStrange situations in daily lifethat happens in micro cosmos [2/2]

. . . . . . .

ClassicalPhysics

QuantumPhysics

The laser changes the speed of the car.It’s the laser control that gives the car it’s speed. Always different colors of clothes

though they don’t communicate.

The measuring changes the high of the car so it cannot pass the tunnel.The cat is both dead and aliveuntil something controls it.

Quantum PhysicsQuotationQuantum PhysicsQuotation

Niels Bohr:If you are not confused by quantum physicsthen you haven’t really understood it.

Richard Feynman:I think I can safely saythat nobody understands quantum physics.

J.B:Haldane:The universe is not only more strange than we suppose,but more strange that we are able to suppose.

William D. Phillips:Entanglements, along with the superposition states,is the strangest thing about quantum physics.

Daniel Greenberger:Einstein said that if quantum physics were correct, then the world would be crazy.Einstein was right, the world is crazy.

Davied Bohm:The most fundamental theory now availableis probabilistic in form, not deterministic.

KvantefysikkInnføringKvantefysikkInnføring

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Et

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2

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Fysikk Matematikk

0 1 2 3 … 0 1

Quantum PhysicsStatistics - Discrete Variables - Continuous VariablesQuantum PhysicsStatistics - Discrete Variables - Continuous Variables

ProbabilityProbability density

Total probability

Expectation value

Variance

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N

NP i

i

0i

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dx)x(

dx)x()x(f)x(f

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Discrete Variables Continuous Variables

KvantefysikkKvantefysikk

Kvantefysikk: Størrelser som inngår i beskrivelse av materien og dens vekselvirkningkan bare anta bestemte, kvantiserte, verdierog 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.

Usikkerhetsrelasjon (uskarphetsrelasjon):2

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