Foundations track

• Quantum States: how a qubit differs from a classical bit, what superposition means, and how the Bloch sphere gives you a way to picture it. Free, no account required.
• Quantum Evolution: how a qubit's state changes over time, covering unitary operations, quantum gates, and the operation sequences that map onto real circuit diagrams.
• Quantum Measurement: what happens when you measure a qubit, covering the Born rule, measurement bases, and why observing a quantum state changes it irreversibly.
• Multi-Qubit System: moving beyond a single qubit, covering tensor products, controlled gates, entanglement, the four Bell states, and the math for reasoning about combined systems.
• Open Quantum System: what happens when a qubit isn't perfectly isolated, covering the density-matrix formalism, noise, decoherence, and entropy.