Learn quantum by answering
Bad Qubits
Learn quantum by playing. Wake up in a valley and rebuild a quantum computer in The Quest, build a streak in a Quiz Run, browse the whole Question Bank, or run the narrative Story Mode — every answer is checked live by an in-browser quantum simulator, never hardcoded, and each game ends in a debrief that links to the real physics.
Four ways to play
The Quest
Wake in the valley, follow the hum, rebuild the machine — a story campaign across the entire curriculum, on keyboard or touch.
Quiz Run
A scored sprint through a deck of questions — streaks, lives, and an end-of-run rank.
Question Bank
Filter every question by level, track, and type. Answer any one and get the debrief.
Story Mode
The “Bad News”-style game: run a quantum channel and make the truth go viral.
Prefer the structured course?
Every question links back to a full lesson. Jump into any level, or open the sandbox.
beginner
Math foundations, qubits, gates, measurement, entanglement, and your first algorithms.
intermediate
Formalism, the QFT, Grover, Shor, VQE/QAOA, simulation, and error detection.
advanced
Quantum information, error correction, fault tolerance, topological codes, and complexity.
964 lessons in all · open the playground →
What’s under the hood
One real simulator
Questions, lessons, and the game run on the same from-scratch state-vector engine — live amplitudes, probabilities, and Bloch vectors. Nothing is faked.
Answers you can trust
Every computational answer is derived by running the circuit through the simulator and re-checked in CI — never hand-typed, never hardcoded.
Write real circuits
Some questions ask you to build a circuit; your code runs in a sandbox and is graded against the simulator’s own output.
Accurate & cited
Original explanations grounded in open sources like MIT OCW, the Qiskit textbook, and Nielsen & Chuang.