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Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● Why study Quantum Mechanics?
● Lecturer: Prof. Woo-Young Choi (최우영) Room: B625, Tel: 02-2123-2874 Email: [email protected], Web: tera.yonsei.ac.kr
● Prerequisites- Curiosity - Basic understanding of ‘waves’ (E&M waves)
- Basic understanding of linear algebra
● Goals
- Understand basics of QM - Learn certain applications of QM for EEE including quantum information
... Dass ich erkenne, was die Welt Im Innersten zusammenhält ... (Goethe, Faust)
… That I may understand whatever binds the world’s innermost core together …
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● Topics (Tentative and subject to changes)
1. Toward quantum mechanics
2. Schroedinger wave equation
3. Time-dependent Schroedinger wave equation
4. Eigen states and operators
5. Quantum information
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● Textbooks
http://iffwww.iff.kfajuelich.de/~ekoch/QM10
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● Grades - 2 x 35 points (1st test: Oct. 15 during the class)- Review presentation in English: 20 points - Attendance and class participation: 10 points
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● 19th century
- Industrial Revolution (1760 – 1840)
- Collapse of Spanish, French (Napoleon), Chinese
- For example, British Empire
- Queen Victoria (1819 – 1901)
- Almost ¼ of the entire world population
The most powerful country in entire human history!
- Growing influence of British, German, Russian Empires, and US
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● 19th century scientists
Michael Faraday (1791-1867)
Heinrich Hertz (1857 – 1894)
James Clerk Maxwell(1831-1879)
Understanding of E&M
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● 19th century scientists
William Hamilton(1805-1865)
Hamiltonian Mechanics
Ludwig Boltzmann (1844 – 1906)
Statistical Mechanics
William Thomson (aka Lord Kelvin)
(1844 – 1906)
Thermodynamics Understanding of classical mechanics and thermodynamics
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● 19th century technologiests
George Stephenson(1781-1848)
First railway line using steam locomotives
Alexander Graham Bell(1847-1922)
First practical telephone
Gottlieb Daimler (1834-1900)
High-speed petrol engine
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● In 19th century,
- Many especially in European countries economically very affluent,(Colonies, new technologies)
- Scientists full of optimism (Many new discoveries and fairly good understanding of these)
Very willing to try various new experimental and theoretical approaches
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● But a puzzling experimental result: Blackbody radiation
Rayleigh-Jeans Law:3
8 kTc
Planck Law approaches R-J Lawwhen hν<<kT.
Planck suggested in 1901 that vibrating atoms only radiate or absorb energy in discrete packetsEn = n h
Fitted the measurement well withh = 6.63 x 10-34 J sec
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● Another puzzling experimental result: Photoelectron effects
- Amount of emitted electrons depends on light intensity
- Same minimum voltage for current flow regardless of light intensity
Same max. kinetic energy for emitted electrons regardless of light intensity?
What determines the max. kinetic energy of emitted electrons?
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
(Max. kinetic energy of emitted electrons)
These cannot be explained by wave nature of light.
Larger intensity => larger E-fieldBut larger E-field inserts larger force (F=qE) and therefore photoelectronics should have larger kinetic energy
- No electron emission if is smaller than a certain value- Kmax increases with
photonE hEinstein’s explanation: Light delivers energy in chunks (photons)! (1905)
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● Furthermore …
If light has particle property, other particle-like matters have wave property
● De Broglie’s hypothesis (1924)
For matter waves, = h/p
Quantum Mechanics (14/2) W.-Y. Choi
Lect. 1: Introduction
● Double-slit experiment (Dr. Quantum – Double Slit Experiment in Youtube)
- For any waves, well-known phenomenon
- For particles such as electroncs?
(Dr. Quantum – Double Slit Experiment in Youtube)