A quantum state vector describes the complete state of a quantum system. For n qubits, the state vector has 2ⁿ complex amplitudes — one for each possible measurement outcome. The probability of measuring a particular bitstring is the squared magnitude of its amplitude.
This visualizer displays each amplitude as a bar whose height represents probability and whose color encodes phase. Apply gates to individual qubits and watch how the full state vector transforms. With multiple qubits, entangling gates like CNOT create correlations that cannot be described by independent single-qubit states.
The exponential growth of the state vector — 2 amplitudes for 1 qubit, 64 for 6 qubits — is both the source of quantum computing's power and the reason classical simulation becomes intractable for large systems.