Table of Contents

# Building a quantum model: Postulates and Experiment

## In-class Content

### Goals

Goals: Students should be able to:

- articulate that the mathematics of quantum mechanics constitutes a mathematical model of physical phenomena.
- articulate that the state of a system is the condition of the system.
- articulate that the quantum state is described by a vector. The quantum state vector represents all of the information we can know about a physical system.

### Whole Class Discussion

- What is a scientific model? Can you give some examples? Why are they important? What are their limitations?
- What do we mean by the phrase “the state of a physical system”?

### Lecture

- The State Postulate “The state of a quantum mechanical system, including all the information you can know about it, is represented mathematically by a normalized ket $|\psi\rangle$.”
- We want to describe the state of these neutral silver atoms by describing the intrinsic angular momentum.
- The Stern-Gerlach experiment will help us to determine the state of the electron in the outer shell of the silver atoms.

### Lab:

- Introduction to the SPINS program (Lecture, 10 minutes)
- Terminology for the Stern-Gerlach Experiment (Lecture, 5 minutes)
- Probabilities in the z-direction for a Spin-$\frac{1}{2}$ System (Simulation, 10 minutes)
- Probabilities for Different Spin-$\frac{1}{2}$ Stern Gerlach Analyzers (Simulation, 15 minutes)