# David Tong: Lectures on Applications of Quantum Mechanics

This is an advanced course on quantum mechanics. It covers a wide range of topics, including an introduction to condensed matter physics and scattering theory. Please do email me if you find any typos or mistakes.

PostScript
PDF

These are the lecture notes given to final year undergraduates at the University of Cambridge. The
material in these lectures can also be found in the Lectures on Solid State Physics and the
Lectures on Topics in Quantum Mechanics.

# Content

**1. Scattering Theory: PDF**

Scattering in one dimension, reflection and transmission coefficients, S-matrix, bound states, resonances; Scattering in three dimensions, the cross-section, the scattering amplitude, partial waves, phase shifts and the optical theorem, a hard sphere, bound states and resonances again; the Lippmann-Schwinger equation, the Born approximation, Yukawa and Coulomb potentials, the Born expansion; Rutherford scattering, the hydrogen atom;**2. The Variational Method: PDF**

The variational method; the helium atom; bound states, the Yukawa potential, the virial theorem; excited states.**3. Band Structure: PDF**

Electrons in one dimension, tight-binding, nearly free electrons, Floquet matrix, Bloch's theorem; Bravais lattices, cubic, BCC and FCC, the Wigner-Seitz cell, the reciprocal lattice, the Brillouin zone; band structure, crystal momentum, crysallographic notation, nearly free electrons in 3d, tight-binding in 3d; Wannier functions, localised and extended stats, LCAO; Scattering off a lattice, Bragg condition, structure factor, Debye-Waller factor.**4. Electron Dynamics in Solids: PDF**

Fermi surfaces, metals vs insulators, graphene; Bloch electrons; effective velocity and mass, semi-classical equations of motion, Bloch oscillations, holes, Drude model; magnetic fields, cylcotron frequency, Onsager quantisation, de Haas-van Alphen oscillations.**5. Phonons: PDF**

Monotonic chain; diatomic chain, optical and accoustic bands, Peierls instability; Quantization; Field theory.**6. Particles in Magnetic Fields: PDF**

Gauge field, gauge transformation; Landau levels, degeneracy; Aharonov-Bohm effect; Magnetic monopoles, Dirac quantisation; Spin in a magnetic field, spin precession.

# Problem Sheets

**Problem Sheet 1: Postscript PDF**Scattering**Problem Sheet 2: Postscript PDF**Variational Method, 1d Band Structure**Problem Sheet 3: Postscript PDF**3d Band Structure; Fermi Surfaces**Problem Sheet 4: Postscript PDF**Phonons; Particles in a Magnetic Field**Notes on Spherical Bessel Functions: Postscript PDF**

# Quantum Mechanics on the Web

**Applications of Quantum Mechanics**An earlier version of this course by Ron Horgan**Quantum Mechanics**by Robert Littlejohn at Berkeley**Advanced Quantum Mechanics**by Ben Simons in TCM, Cambridge**Solid State Physics**by Steve Simon at Oxford**Solid State Theory**by Manfred Sigrist at ETH, Zurich