Physics 12b
Quantum Physics
Winter 2010

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Course description: An introductory course in quantum mechanics.

Class meetings: Tuesday and Thursday 10:30-11:55 am in 269 Lauritsen, starting January 5, 2010.

Feedback: If you want to send a comment about the course, click here.

Instructor: John Preskill, 206 Annenberg, X-6691,

Recitation leaders:

Milivoje Lukic,

Heywood Tam,


Recitation sessions:
Recitation leaders: Tuesday 8:00-9:00pm, 269 Lauritsen, Milivoje Lukic
Wednesday 7:30-8:30pm, 269 Lauritsen, Heywood Tam


Miguel Bandres,

Chaitanya Rastogi,

Textbook:  Introductory Quantum Mechanics (4th edition) by Richard L. Liboff

We will cover most of the first 8 chapters of Liboff, plus some supplementary material.

Grading: Grades will be based on weekly problem sets (30%), a midterm (30%), and a final exam (40%).

Homework: Problem sets will be posted on this page on Thursday, and will be due in the Physics 12b IN-box in 264 Lauritsen at 5:00 pm the following Thursday. Graded homework will be returned to the Physics 12b OUT-box in 264 Lauritsen by the following Monday morning. Solution sets will be posted on this page. Unexcused late homework will be accepted for half credit up until one week after the due date; there is no credit if your assignment is more than one week late. If your homework will be late for a good reason, you may request an extension before the assignment is due by sending email to that week’s grader.

Honor Code: Discussion with others is encouraged, but the work you hand in must be your own. In particular, do not use homework solutions from previous years or exams and exam solutions from previous years.

Lectures (tentative schedule):
Jan 5.   Quantum interference
Jan 7.
  Hamiltonian mechanics
Jan 12.
Quantum postulates I: states and observables
Jan 14. Quantum postulates II: measurement
Jan 19. Quantum postulates III: evolution (lecture notes)
Jan 21. The density operator (lecture notes)
Jan 26. Decoherence (lecture notes)
Jan 28. What is measurement? (lecture notes)
Feb 2. Particle in a box
Feb 4. Uncertainty principle (lecture notes)
Feb 9. Free particle (lecture notes)
Feb 11. Bound states in one dimension
Feb 16. Harmonic oscillator I: creation and annihilation operators
Feb 18. Harmonic oscillator II: coherent states (lecture notes)
Feb 23. Scattering I: the potential step
Feb 25.
Scattering II: the rectangular potential barrier
Mar 2.
The WKB approximation (lecture notes)
Mar 4. The finite potential well (lecture notes)
Mar 9. The periodic potential (lecture notes)
Mar 11. Entanglement and the Bell inequality

Homework assignments: 
Read Liboff, Chapters 1 and 2.
Problem Set 1, due Jan 14: Uncertainty, Hamiltonian dynamics, and quantum interference. Solutions. Graded by Miguel.
Read Liboff, Chapters 3 and 4.
Problem Set 2, due Jan 21: Eigenstates and eigenvalues. Solutions. Graded by Chaitanya.
Problem Set 3, due Jan 28: Some novel measurements. Solutions. Graded by Miguel.
Problem Set 4, due Feb 4: Density operator and decoherence. Solutions. Graded by Chaitanya.
Read Liboff, Chapters 5 and 6.
Problem Set 5, due Feb 18: Uncertainty. Solutions. Graded by Miguel.
Read Liboff, Chapter 7 through Section 7.4.
Problem Set 6, due Feb 25: Harmonic oscillator. Solutions. Graded by Chaitanya.
Read Liboff, Chapter 7, Sections 7.5 through 7.9.
Problem Set 7, due Mar 4: Damped oscillator and scattering. Solutions. Graded by Miguel.
Read Liboff, Chapter 7, Sections 7.10, 7.11, Chapter 8, Sections 8.1-8.4
Problem Set 8, due Mar 11: Bound states. Solutions. Graded by Chaitanya.

Midterm exam, available Feb. 4 and due Feb 10. Covers all material through Problem Set 4. Solutions.
Sixty exams were received. The median was 87 and the mean was 84. Eleven students scored 100.

Final: available Mar 11 and due Mar 17. Covers everything in the course, emphasizing material from after the midterm.
Cover page with final exam instructions. (You may open this now.)
Final exam. (Open only when you are ready to take the exam.). Solutions.
Fifty-six exams were received. The median was 74 and the mean was 67. Eleven students scored 90 or higher.

Final grades were determined using the formula Grade = 0.3(Homework) + 0.3(Midterm) + 04(Final).
The median final grade was 79 and the mean was 77.
The ranges for letter grades were:

A+       96-100
A         89-95
A-        80-88
B+       75-79
B         65-74
B-        59-64
C+       50-58

There were 5 A+’s, 14 A’s, 13 A-’s, 5 B+’s, 10 B’s, 7 B-’s, 2 C+’s (Total=56).
The mean GPA was 3.49.