Lecture, three hours; discussion, one hour. Requisites: courses 17, 32, 105A. Classical background. Basic ideas of quantum nature of light, wave-particle duality, Heisenberg uncertainty principle, Schrödinger equation. One-dimensional square well and harmonic oscillator problems. One-dimensional scattering, Formal theory, Hilbert spaces, and Dirac notation. P/NP or letter grading.