Exploring Quantum Physics Through Hands-On Projects (Paperback)

Introduction xi

Prologue xv

Important Disclaimer and Warnings xix

Acknowledgments xxiii

About the Authors xxv

1 LIGHT AS AWAVE 1

Newton’s View: Light Consists of Particles 1

Young’s Interference of Light 3

Automatic Scanning of Interference Patterns 6

The Final Nail in the Coffin for Newton’s Theory of Light 8

Light as an Electromagnetic Wave 9

Polarization 11

Optics with 3-cm Wavelength “Light” 11

Real-World Behaviors 16

Double-Slit Interference with Microwaves 17

The Doppler Effect 18

Experiments and Questions 20

2 LIGHT AS PARTICLES 23

The Seed of Quantum Physics: Planck’s Formula 27

The Photoelectric Effect 28

Can we Detect Individual Photons? 36

Low-Cost PMT Power Supplies 38

Listening to Individual Photons 41

Where does this Leave Us? 45

Experiments and Questions 45

3 ATOMS AND RADIOACTIVITY 49

The Need for Vacuum 49

The Mechanical Vacuum Pump 51

The Vacuum Gauge 53

A Very-High-Voltage Power Supply 56

A Vacuum Tube Legow Set 56

Phosphor Screens 59

The Electron Gun 60

The Discovery of the Electron 61

Cathode-Ray Tubes 63

Thomson’s First 1897 Experiment—Negative Charge and Rays are Joined Together 65

Thomson’s Second Experiment—Electrostatic Deflection of Cathode Rays 67

Thomson and the Modern CRT 69

Thomson’s Third Experiment—Mass-to-Charge Ratio of the Electron 72

Measuring e/m with our CRT 74

A Magical Measurement of e/m 77

Thomson’s “Plum Pudding” Model of the Atom 79

Geiger–Mu¨ller Counter 80

a, b, and g 89

The Nature of Beta Radiation 92

The Ionizing Power of Alpha 92

What are Alpha Particles? 95

Rutherford’s Alpha-Scattering Experiment 96

Rutherford’s Planetary Model of the Atom 102

Experiments and Questions 103

4 THE PRINCIPLE OF QUANTUM PHYSICS 107

Emission Spectroscopy 107

Bohr’s Spark of Genius 113

Orbitals and Not Orbits 115

Quantization—The Core of Quantum Physics 117

Experiments and Questions 118

5 WAVE–PARTICLE DUALITY 121

Gamma-Ray Spectrum Analysis 122

What is the Nature of Light? 126

Two-Slit Interference with Single Photons 128

Imaging Single Photons 133

The Answer: Complementarity 135

Matter Waves 137

Matter Waves and the Bohr Atom 137

Experimental Confirmation of De Broglie’s Matter Waves 138

Two-Slit Interference with Single Electrons 142

A Simple TEM 144

Blurring the Line Between Quantum and Classical 148

Particle–Wave Duality in the Macroscopic World 148

Experiments and Questions 149

6 THE UNCERTAINTY PRINCIPLE 151

Wavefunctions 151

The Uncertainty Principle 153

Experimental Demonstration of the Uncertainty Principle 155

Time–Energy Uncertainty 159

Fourier Analysis 159

Bye, Bye Clockwork Universe 163

Experiments and Questions 165

7 SCHRO¨ DINGER (AND HIS ZOMBIE CAT) 167

Real-World Particle in a Box 171

Quantum Tunneling 174

Quantum Tunneling Time 178

Many-Worlds Interpretation 183

Schro¨dinger’s Cat in the Lab 184

Beam Splitters 186

Who Rolls the Dice? 190

The Mach–Zehnder Interferometer 192

“Which-Way” Experiments 197

The Quantum Eraser 199

Experiments and Questions 200

8 ENTANGLEMENT 203

Bell’s Inequalities 205

An Entangled-Photon Source 211

Detecting Entangled Photons 214

High-Purity Single-Photon Source 219

Testing Bell’s Inequality 220

Closing the Loopholes 225

The Age of Quantum Information 226

A Quantum Random-Number Generator 228

Quantum Information 229

Quantum Teleportation 230

Faster-Than-Light Communication 236

Quantum Cryptography 237

Quantum Computing and Technologies for the Future 240

Experiments and Questions 242

REFERENCES 245

SOURCES FOR MATERIALS AND COMPONENTS 249

ABBREVIATIONS 255

INDEX 257