Challenges
Five hand-picked puzzles to turn the sandbox into a guided tour. Pick any one — they're all open from the start.
#01 1 qubit
Flip |0⟩ → |1⟩
The simplest non-trivial move: turn a qubit in |0⟩ into a qubit in |1⟩.
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#02 1 qubit
Reach |+⟩
Put a qubit into an equal superposition: 50% chance of measuring 0, 50% chance of measuring 1.
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#03 1 qubit
Tilt to P(|0⟩) ≈ 0.75
Rotate a qubit so a measurement returns 0 about three-quarters of the time.
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#04 2 qubits
Build a Bell pair
Entangle two qubits into (|00⟩ + |11⟩)/√2 — measure one, the other follows.
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#05 3 qubits
Stretch to a GHZ trio
Extend the Bell idea to three qubits: (|000⟩ + |111⟩)/√2.
Start →Each puzzle watches the circuit you build and reports a state fidelity F ∈ [0, 1] against a target state. F ≥ 0.99 counts as solved; anything in [0.90, 0.99) is "close" and worth tuning. Stuck? Each card has progressive hints.