Volume II · Quantum量子

A state is a direction. Measurement is a question you only get to ask once.

Eight labs: a qubit on a sphere, a measurement that cannot be undone, then Deutsch — the smallest quantum advantage that is actually an advantage.

Start with superposition Skip to decoherence

In English

A qubit is not a magical bit that is 0 and 1 at once. It is a direction you can rotate, and a question you can ask only once. This volume builds that picture until Deutsch — the smallest demo that quantum looking is actually cheaper.

Try this: Start with Superposition and drag the sphere. Come back here if a later lab feels abstract.
Keep this: States are directions. Measurement is a one-shot question.

The stack · click a layer

What this is

A working 1- and 2-qubit state vector you can rotate, measure, entangle, and decohere. Deutsch’s algorithm is the smallest quantum advantage that is actually an advantage.

What this is not

Not a hardware emulator and not a substitute for Nielsen & Chuang. Phases, Born-rule shots, and density-matrix damping are computed for real. The Bloch drawing is a projection.