Gates and Circuits

Build and read circuits: single-qubit gates, CNOT, Bell states, depth, OpenQASM 3 and Qiskit.

7 lessons23 exercises80 min

1. 01Pauli gates: X, Y, ZThe three flips every circuit is built from, as matrices and as Bloch rotations.10 min
2. 02Phase and rotation gatesS, T, P and the RX/RY/RZ family: fine control of a qubit, and why T matters.12 min
3. 03Two-qubit gates: CNOT, CZ, SWAPControls and targets, the matrices, and how CZ is a CNOT in disguise.12 min
4. 04Entanglement and the Bell statesBuild the four Bell states, test them with correlations, and see why they cannot be factored.14 min
5. 05Phase Kickback: The Algorithm SecretHow a CNOT can change its own control: a target in |−⟩ sends a phase back, the trick inside every oracle and phase estimation.12 min
6. 06Reading a circuit: depth, width and costColumns, layers, depth, two-qubit count: the numbers QubitLab shows and why they predict hardware results.10 min
7. 07Two languages: OpenQASM 3 and QiskitHow the same circuit is written in both, and how QubitLab keeps them in sync without running your code.10 min