Visualizations

40 experiments you can actually run

These are live simulations, not videos or canned animations. Every slider you drag genuinely re-solves the physics in your browser — the amplitudes, the interference pattern, and the measurement statistics are all computed from the state you built, on the spot.

The Double-Slit Experiment

Fire electrons one at a time and watch stripes appear that no particle should make.

Superposition & Measurement

Build a quantum state gate by gate, then find out what measuring it actually destroys.

The Bloch Sphere

Every possible state of a single qubit, as one point on a globe you can spin.

The Stern-Gerlach Experiment

Measure a beam sideways and it forgets which way was up — put it back through the first magnet and half of it comes out down.

Particle in a Box

Trap a particle between two walls and only certain energies survive — then lower the walls and watch it leak out through them.

The Photoelectric Effect

Turn the lamp up as far as you like. Below a certain colour, not one electron comes out.

Blackbody Radiation

The classical curve does not overshoot slightly — it goes to infinity, and fixing that took quantising light itself.

Entanglement

Two qubits whose answers always match — without either one carrying the answer.

Quantum Tunneling

A particle without the energy to climb the wall, appearing on the other side anyway.

Grover's Search

Find one item in a million with a thousand guesses — by making the wrong answers cancel.

Decoherence

Watch a qubit forget — the arrow retracts into the sphere and takes the phase with it.

The Bell Test

Race a hidden-variable universe against a real one and watch it stall at exactly 2.

Quantum Teleportation

A state crosses the room without the qubit — and still waits on two ordinary bits sent the slow way.

Superdense Coding

Two classical bits down a single qubit. Take the entangled pair away and exactly one of them vanishes.

The Quantum Harmonic Oscillator

A ladder of evenly spaced rungs, and one packet that swings like a marble in a bowl without ever spreading.

Wave Packets and Scattering

Draw a landscape, fire a packet at it, and watch some of it bounce off a barrier it had plenty of energy to cross.

Models of the Hydrogen Atom

Bohr’s orbits and Schrödinger’s clouds predict the same spectrum — and disagree about everything else.

The Mach-Zehnder Interferometer

Two beams, each carrying half the light, meeting at a detector that never clicks — until you lengthen one path by half a wavelength.

Deutsch–Jozsa: The First Quantum Speedup

One call to a black box settles a question that can cost a classical computer half a million.

Spin Precession

Put a magnetic field on the Bloch sphere and the arrow starts to turn — the same physics as an MRI scanner and as every RX gate.

Uncertainty as a Fourier Trade-off

Squeeze a packet in position and its momentum spreads to compensate — watch the Gaussian land exactly on the ħ/2 floor that nothing beats.

How a Laser Works

Pump atoms up faster than they fall and one stray photon becomes a beam of identical copies — take one level away and it never can.

Alpha Decay: Tunneling with a Half-life

Uranium’s four-billion-year half-life is one number: the chance, per knock, that an alpha particle is simply on the other side of a wall it cannot climb.

Davisson–Germer: Electron Diffraction

Fire electrons at a nickel crystal and a peak appears at 54 V and 50° — exactly where a 0.167 nm wave would put it. The experiment that proved de Broglie.

Quantum Key Distribution

Let Eve intercept the photons and watch a quarter of the key go wrong — she cannot listen more quietly, and 11% is where Alice and Bob stop trusting it.

Quantum Fourier Transform

The transform at the heart of Shor’s algorithm, with every phase laid bare.

VQE and the Barren Plateau

A classical optimiser hunts a ground-state energy across a landscape that goes flat as the qubit count grows.

Shor's Algorithm: Period Finding

The one quantum step inside factoring — finding a hidden period, not the factors themselves.

The Surface Code

Why one error-corrected qubit costs a hundred real ones, and what happens when you skimp on distance.

Decoder Duel: Lookup vs Learned

A neural decoder trains in your browser and chases majority vote — which, on this code, is provably unbeatable.

The Quantum Eraser

Erase which-path information after the photon has already been detected, and find the interference waiting in the bookkeeping.

Quantum Phase Estimation

An eigenvalue nobody can measure, written into spare qubits as a phase and read back as a number.

Band Structure

Switch a row of atoms on under a free electron and whole ranges of energy become forbidden — then count electrons to see which solids conduct.

Fermions and Bosons

Put two particles in one well and swap them. A minus sign you cannot see carves a hole where they would meet — and stacks the periodic table.

Tomography and No-Cloning

Learn an unknown state from thousands of copies measured three ways — and try to build the copier that would make it cheap.

Mixed States and the Density Matrix

The arrow inside the sphere, as a matrix: purity is its length, a mixture is not a superposition, and half of a Bell pair is the most mixed a qubit gets.

Wavefunctions in Three Dimensions

Box, oscillator, rotor and hydrogen as the probability clouds they are — no edge, no isosurface, and a plane you can drag through the nodes.

Phase Space and the Wigner Function

A quantum state as a landscape over position and momentum — and a single photon digs it below zero, where no probability can go.

Majorana Stars

The Bloch sphere for bigger spins: 2j points instead of one — rotate them and they turn together, squeeze them and they fly apart.

The HHL Algorithm

Solve Ax = b without ever computing x — phase estimation reads out an eigenvalue, and a controlled rotation divides by it.