Learn Quantum Computing with Qiskit
Interactive lessons that run entirely in your browser. Progress is saved locally in IndexedDB — nothing leaves your machine.
math
Complex Numbers and Vectors
The complex-number and vector-space toolkit every later lesson leans on, i, modulus, inner products, and norms.
9 min read
Matrices as Linear Operators
How a matrix transforms a vector, why gate order matters, and a first look at the Pauli-X matrix in action.
8 min read
Eigenvalues and Eigenvectors
The states a gate leaves alone (up to a scalar), why that scalar is called an eigenvalue, and where this shows up all over the algorithms track.
10 min read
Unitary Matrices
The adjoint, the unitary condition, and why every quantum gate (but not measurement) has to satisfy it.
10 min read
Tensor Products and Multi-Qubit State Space
How single-qubit spaces combine into the 2^n-dimensional space multi-qubit states live in, and why entanglement means "not a tensor product."
8 min read
foundations
What is a Qubit?
Classical bits vs. qubits, superposition, and how Qiskit represents quantum state.
3 min read
Single-Qubit Gates: X, H, and Z
Apply the Pauli-X, Hadamard, and Pauli-Z gates and watch the state vector move on the Bloch sphere.
6 min read
Entanglement & Bell States
Combine Hadamard and CNOT to build the Bell state and see two-qubit correlation.
7 min read
How Circuits and Gates Take Their Arguments
The different shapes qubit and parameter arguments come in, single values, lists, registers, and register indices.
8 min read
Measurement, Shots, and Running on a Simulator
Why measuring collapses a qubit, what "shots" are, and how Qiskit Aer turns a circuit into counts.
12 min read
algorithms
Superposition and Interference at Scale
Put every qubit into superposition at once with H, and see amplitudes cancel exactly via interference.
9 min read
Phase Kickback
The ancilla-in-|−⟩ trick that turns a bit-flip gate into a phase gate on the control qubit.
9 min read
Oracles and Black-Box Functions
What a quantum oracle is, why it has to be reversible, and how to build one from a classical boolean function.
10 min read
Constant and Balanced Functions
What "constant" and "balanced" really mean, how many balanced functions exist, and why a classical algorithm needs more than half the domain in the worst case.
11 min read
The Deutsch-Jozsa Algorithm
One oracle query to tell constant from balanced, the first algorithm with a proven quantum speedup.
14 min read
The Bernstein-Vazirani Algorithm
Same circuit as Deutsch-Jozsa, one query, but this time it reads out an entire hidden bitstring instead of one bit of information.
12 min read
Amplitude Amplification
The geometric picture behind Grover's algorithm, two reflections make a rotation, and why unstructured search takes only O(√N) queries instead of O(N).
10 min read
Grover's Algorithm
The full circuit, oracle plus diffusion operator, worked exactly for a 2-qubit (4-item) search.
13 min read
The Quantum Fourier Transform
The quantum analog of the discrete Fourier transform, built from H and controlled-phase gates, and the circuit that computes it exactly.
13 min read
Quantum Phase Estimation
Reading out a unitary's eigenvalue as a binary fraction, using controlled powers of U and an inverse QFT.
18 min read
Order-Finding and Factoring
The classical number-theory reduction that turns factoring into order-finding, and why a unitary built from modular multiplication encodes the order as an eigenvalue.
12 min read
Shor's Algorithm
Every piece from the last three lessons, QPE, the order-finding reduction, and the modular-exponentiation oracle, combined into the complete factoring algorithm.
18 min read