Introduction to Quantum Mechanics: Mathematics GU4391 (fall 2024)

Peter Woit (woit@math.columbia.edu)
Mathematics 421

Monday and Wednesday 2:40-3:55pm
Mathematics 417

Office hours:  please feel free to stop by my office (Math 421, down the hall from classroom) anytime, I'm often there and will have some time to talk. I will usually be available after class Monday and Wednesday.  Join me for a cookie up in the math lounge (Math 509), then we can talk down in my office.

Teaching Assistant:  Davis Lazowski (davis.lazowski@columbia.edu)


Course Summary and Prerequisites

This course will be an introduction to the subject of quantum mechanics, from a perspective emphasizing the role of Lie groups and their representations.  Most of the standard material and examples from a conventional first physics course on the subject will be covered, but with much greater attention to the mathematical ideas behind the standard formalism and usual calculational techniques. 

No specific background in physics will be assumed, although an elementary physics course of some kind would be helpful.  The mathematical prerequisites are multi-variable calculus (as in Calculus IV), and Linear Algebra.  This course is open to both undergraduate and graduate students.  It can be taken independently and in addition to any of the Physics department courses on quantum mechanics.

Lecture Notes/Book/Videos

The lecture notes from previous versions of this course have been turned into a book, see here.   During this course I expect to be revising some of the material in the book, and maybe adding some new chapters.  The most recent version will always be available here

During the semester I expect to cover roughly the material in the first 23 chapters of the book.  Before each class, please try and read the chapter in the syllabus announced for that class and come prepared with questions about whatever you don't understand.  I hope to devote much of the time in each class to going over material students are finding confusing, rather than repeating everything that is in the notes.

The 2020-21 version of the course was online-only because of COVID and videos are available on Youtube.

Problem Sets and Exams

There will be problem sets due roughly every week or two, a midterm and a final exam. The final exam is scheduled for Wednesday, December 18, 1:10-4pm.  Use of notes is allowed during the exams.  Grading will be based on these according to: 50 % final exam, 25 % midterm exam, 25 % problem sets.

First problem set will be due Wednesday, September 18.
Problems 1-4 in appendix B.1 of the book

Second problem set will be due Monday, September 30.
Problems 2 and 4 in appendix B.2 of the book
Problems 2,3,4 in appendix B.3 of the book

Third problem set will be due Wednesday, October 9.
Problems  1,2,3 in appendix B.4 of the book
Problem 1 in appendix B.5 of the book

Fourth problem set will be due Wednesday, October 30.
Problems 1,2,3,5 in appendix B.6 of the book

Fifth problem set will be due Monday, November 18.
Problems 1,2,3,4 in appendix B.7 of  the book

Sixth problem set will be due Monday, December 2.
Problem 1 in appendix B.8  and problems 1,2.3 in appendix B.9 of the book

Seventh problem set will be due Monday, December 9 (can be handed in up to final exam).
Problems 1,2,3,4 in appendix B.10 of the book

Tentative Schedule of Lectures

Chapter numbers correspond to the course textbook, Quantum Theory, Groups and Representations.


Wednesday, September 4: Introduction and overview, the example of U(1) (Chapters 1, 2)
Monday, September 9: More U(1), some general theory (Chapters 1, 2)
Wednesday, September 11: More general theory and U(1) (Chapters 1,2), two-state systems, the qubit (Chapter 3)
Monday, September 16: More about the qubit and SU(2) (Chapter 3), Lie algebras (Chapter 5)
Wednesday, September 18:  Rotation and spin groups (Chapter 6)
Monday, September 23: Spin 1/2 particle in a magnetic field (Chapter 7)
Wednesday, September 25: Spin 1/2 particle in a magnetic field (Chapter 7), Representations of SU(2) and SO(3) (Chapter 8)
Monday, September 30: More about representations of SU(2) and SO(3) (Chapter 8)
Wednesday, October 2: Tensor product (Chapter 9)
Monday,  October 7:  Review
Wednesday, October 9:  Midterm exam (through Chapter 9)
Monday, October 14:  Momentum and the free particle (Chapter 10)

Wednesday, October 16:  Fourier analysis  (Chapter 11)
Monday, October 21: More Fourier analysis, distributions (Chapter 11)
Wednesday, October 23: Position and the free particle (Chapter 12)
Monday, October 28:  The propagator (Chapter 12), the Heisenberg group (Chapter 13)
Wednesday, October 30: The Heisenberg group and the Schrodinger representation (Chapter 13), the Poisson bracket (Chapter 14)
Wednesday, November 6: The Poisson bracket and symplectic geometry (Chapter 14), the moment map (Chapter 15)
Monday, November 11: The  moment map  (Chapter 15), quadratic polynomials as a Lie algebra (Chapter 16)
Wednesday, November 13: The symplectic group (Chapter 16)
Monday, November 18: Quantization (Chapter 17)
Wednesday, November 20: Semi-direct products and the Euclidean group (Chapter 18)
Monday, November 25:  The quantum free particle as representation of the Euclidean group (Chapter 19)
Monday, December 2: Central potentials and the hydrogen atom (Chapter 21)
Wednesday, December 4: The Harmonic oscillator (Chapter 22)
Monday, December 9:  Review



Final exam is scheduled for  Wednesday,  December 18, 1:10-4pm

Other Textbooks

A standard physics textbook at the upper-undergraduate to beginning graduate level should be available to consult for more details about the physics and some of the calculations we will be studying.  A good choice for this is

Principles of Quantum Mechanics
, by Ramamurti Shankar. Springer, 1994.

which does a good job of carefully working out the details of many calculations. Two good undergraduate-level texts are

A Modern Approach to Quantum Mechanics, John S. Townsend, University Science Books, 2000.
Introduction to Quantum Mechanics, David J. Griffiths, Prentice-Hall, 1995.


Several suggestions for standard physics textbooks that provide good references for some of the topics we(The following is from when I last taught the course, will be updated soon for the spring 2022 version). will be considering are:

Quantum Mechanics, Volume 1, by Cohen-Tannoudji, Diu and Laloe. Wiley, 1978
The Feynman Lectures on Physics, Volume III, by Richard Feynman. Addison-Wesley 1965.
Lectures on Quantum Mechanics, Gordon Baym.
Quantum Mechanics, Volumes 1 and 2, Albert Messiah.
Quantum Mechanics, Volume 1, Kurt Gottfried.
Introduction to Quantum Mechanics, David J. Griffiths.
Quantum Mechanics and the Particles of Nature: an Outline for Mathematicians, Sudbery. Cambridge 1986 (unfortunately out of print)

Some other books at various levels that students might find helpful:

More mathematical:

An Introduction to Quantum Theory, by Keith Hannabuss. Oxford, 1997.
Quantum Mechanics for Mathematicians, by Leon Takhtajan. AMS, 2008.
Lectures on Quantum Mechanics for Mathematics Students, by L.D. Fadeev and O.A. Yakubovskii. AMS, 2009.
Linearity, Symmetry and Prediction in the Hydrogen Atom, Stephanie Singer, Springer, 2005. (On Springerlink at this URL)

Some more from the physics side, available via Springerlink:

Quantum Mechanics, Franz Schwabl.
Lectures on Quantum Mechanics, Jean-Louis Basdevant.
Quantum Mechanics, Daniel Bes.

A classic:

The Theory of Groups and Quantum Mechanics, Hermann Weyl.

Also emphasizing groups and representations, but covering mostly different material:

Group theory and physics, Shlomo Sternberg.

More advanced, from the point of view of analysis:

Mathematical Methods in Quantum Mechanics, Gerald Teschl

Recommended sources on Lie groups, Lie algebras and representation theoy:

Naive Lie Theory, John Stillwell
Groups and Symmetries: From Finite Groups to Lie Groups, Yvette Kossmann-Schwarzbach
An Elementary Introduction to Groups and Representations, Brian C. Hall
Lie groups, Lie algebras and representations, Brian C. Hall
Representation Theory, Constantin Teleman

For more about Fourier analysis, see notes from my Spring 2020 Fourier analysis class.

Online Resources

Lecture notes for a course on Quantum Computation, John Preskill (especially Chapters 1-3)


Previous Courses

Introduction to Quantum Mechanics, Fall 2012: Math W4391
Introduction to Quantum Mechanics, Spring 2013: Math W4392
Introduction to Quantum Mechanics, Fall 2014: Math W4391
Introduction to Quantum Mechanics, Spring 2015: Math W4392
Introduction to Quantum Mechanics, Fall 2020: Math GU4391
Introduction to Quantum Mechanics, Spring 2021: Math GU4392
Introduction to Quantum Mechanics Spring 2022: Math GU4291