Circuit Bench¶

All circuit notes in one place. Each one is self-contained: pick whatever interests you, or follow the Learning Path for a structured progression.

New notes will appear as the workbooks need them. Watch the repo to get notified.

Find the circuit files¶

Every note has a Files on the bench section with direct links to its runnable OpenQASM 2.0 program, expected output, and circuit diagram where one is available.

In the repository, those files live together under cookbook/recipes/:

cookbook/recipes/01-bell-state/
├── README.md       # the circuit note
├── bell.qasm       # the runnable circuit
├── expected.txt    # the result to compare against
└── circuit.png     # the circuit diagram

Some notes need more than one circuit. Circuit Bench 00 compares three one-qubit programs, Circuit Bench 03 has constant and balanced oracles, and Circuit Bench 11 has three noise scales. Their file lists make those roles explicit.

Run a circuit¶

Open a circuit note and choose a .qasm file from Files on the bench.
Load or paste it into the Quokka app or cloud notebook, or another runner that accepts OpenQASM 2.0.
Start with 1024 shots unless the note says otherwise. Deterministic circuits should concentrate on one result; probabilistic circuits should approach the stated distribution.
Compare the result with expected.txt and the note's Run it section. Compare the pattern, not exact shot counts.
Check the runner's bit-string convention before interpreting a result. Some tools print the highest-index classical bit first; the notes state the register order when it matters.

The Getting Started page walks through the Quokka setup and a first Bell-state run.

Extend and experiment¶

Treat each committed .qasm file as a reference circuit. Copy it before changing it, then use the same loop for every experiment:

Predict what should change in the output and why.
Change one thing: one gate, angle, oracle term, measurement basis, or repetition count.
Run under the same conditions, including the same number of shots.
Compare with the reference output.
Explain the difference in terms of state preparation, phase, interference, or measurement.

A small record is enough:

Change	Prediction	Observed result	Explanation
One controlled modification	What should move or stay fixed?	Counts or probabilities	Which circuit mechanism caused it?

Each note ends with experiments chosen for that circuit. They are deliberately small: the point is to isolate a mechanism, not to turn a teaching circuit into an advantage claim.

Foundations¶

The fundamentals: one to three qubits, a handful of gates, and the first circuits where quantum behaviour becomes visible.

#	Circuit note	Qubits	Key concept	Status
00	Reading a Quantum Circuit	1	Gates, Bloch sphere, unitary rotation, measurement bases	✅ Published
01	Bell State	2	Entanglement, measurement correlation	✅ Published
02	Teleportation	3	Classical feedback, the teleportation protocol	✅ Published
03	Deutsch-Jozsa	3	Oracles, phase kickback, quantum speedup	✅ Published

Algorithms and applications¶

Optimisation, simulation, and search: the circuits where quantum algorithms start to show their structure.

#	Circuit note	Qubits	Key concept	Status
04	Bernstein-Vazirani	4	Hidden string discovery in one query	✅ Published
05	Simon's Problem	4	Hidden period, exponential speedup	✅ Published
06	Grover's Search	3	Unstructured search, quadratic speedup	✅ Published
07	QAOA for MaxCut	3	Combinatorial optimisation, variational methods	✅ Published
08	VQE for H₂	2	Quantum chemistry, molecular simulation	✅ Published
09	Quantum Fourier Transform	3	Fourier analysis on a quantum register	✅ Published

Advanced techniques¶

Phase estimation, quantum counting, and the techniques that power the big algorithms.

#	Circuit note	Qubits	Key concept	Status
10	Quantum Phase Estimation	4	Eigenvalue extraction, precision measurement	✅ Published
11	Error Mitigation (ZNE)	2	Zero-noise extrapolation, practical noise reduction	✅ Published
12	Quantum Counting	4	Counting solutions without finding them	✅ Published