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The Strange Quantum World
There's another world below atoms
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Quantum Physics
Follow nature from wave functions and atoms into qubits, hardware, sensing, secure communication, and quantum fields.
Reality before vocabulary
Foundations
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Superposition
The particle is everywhere at once
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The Wave Function
ψ(x,t) — the math of possibility
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Measurement
Looking is what makes things real
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The Double Slit
One particle going through two slits
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Wave-Particle Duality
Light is both — and so are you
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Uncertainty
Some things can't be known at the same time
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Quantum Tunneling
Particles walk through walls
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The Schrödinger Equation
The equation that runs the universe
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Stationary States
Standing waves in a quantum world
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The Particle in a Box
What happens when you trap a wave
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Hydrogen
How an electron orbits without orbiting
How matter gets its structure
Atomic & Molecular Physics
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Spin
Particles spin without spinning
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The Stern-Gerlach Experiment
The experiment that found spin
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Pauli Exclusion
Why every atom has a shape
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Multi-Electron Atoms
When electrons have to share a house
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Molecular Orbitals
Two atoms, one shared cloud
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Chemical Bonding
Why atoms stick together
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Spectroscopy
How light tells you what something is
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Lasers
Coherent light, plain and simple
From bits to qubits
Quantum Information
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Bits and Qubits
Beyond zero and one
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The Bloch Sphere
Every quantum state is a point on a sphere
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Single-Qubit Gates
Rotations of the Bloch sphere
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The CNOT Gate
When two qubits become one
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Entanglement
Two particles, one shared destiny
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Bell States
Einstein was wrong about this one
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Quantum Teleportation
Quantum information at any distance
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The No-Cloning Theorem
You can't copy a quantum state
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POVMs
Measurement isn't always yes-or-no
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Density Matrices
Quantum states with imperfect information
Algorithms as physical operations
Quantum Computing
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Quantum Circuits
Reading the circuit diagram
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Universal Quantum Gates
All quantum logic from a small set
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Deutsch-Jozsa
The first quantum advantage
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Grover Search
Searching faster than possible
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Quantum Fourier Transform
The quantum Fourier transform
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Shor's Algorithm
How quantum computers break encryption
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Variational Quantum Eigensolver
Solving chemistry with quantum hardware
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QAOA
Approximating impossible optimizations
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Quantum Machine Learning
When neural networks meet qubits
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NISQ Computing
What today's quantum computers can do
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Fault Tolerance
Building reliability from unreliability
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Surface Codes
The error-correcting code that might win
Turning equations into machines
Quantum Hardware
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Superconducting Qubits
Qubits made of supercooled metal
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Trapped Ions
Qubits made of single floating atoms
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Photonic Qubits
Qubits made of light
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Topological Qubits
The qubit that's intrinsically protected
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Neutral Atoms
Qubits made of atoms held by lasers
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Spin Qubits
Qubits inside silicon — the same stuff as your computer
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Decoherence
Why quantum computers have to be cold
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Cryogenics
How to make something colder than space
Measurement pushed to the edge
Quantum Sensing
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Quantum Sensing
Measuring the universe more precisely than physics should allow
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Atomic Clocks
The most accurate clocks in existence
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NV Centers
A defect in diamond that can sense a single electron
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Quantum Gravity Sensing
Detecting the pull of a single grain of rice
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LIGO
How LIGO detected colliding black holes
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Quantum Imaging
Photographing things with light that never touched them
Security from physics
Quantum Cryptography
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The Classical Cryptography Problem
Quantum computers will break the internet
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BB84
BB84 — the original quantum-secure key exchange
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E91
Bell-state cryptography
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Post-Quantum Cryptography
Post-quantum cryptography — fighting fire with fire
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Quantum Random Number Generation
True randomness from a quantum coin flip
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The Quantum Internet
What a real quantum internet would look like
Fields under every particle
QFT & Beyond
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The Quantum Vacuum
Empty space is full of activity
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Quantum Electrodynamics
How light and matter actually interact
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Feynman Diagrams
Drawing the impossible
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Path Integrals
All paths at once
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The Standard Model
What the universe is made of, plain and simple
What quantum theory says about reality
Foundations & Philosophy
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The Measurement Problem
Why measurement is still a mystery
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Many Worlds
Every measurement creates a universe
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Copenhagen
The standard interpretation, examined
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Pilot Wave Theory
What if particles really do have positions?
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QBism
What if the wave function is just a tool?