qiskit.quantum_info.entropy

entropy(state, base=2)

Calculate the von-Neumann entropy of a quantum state.

The entropy $S$ is given by

Parameters

• state (Statevector orDensityMatrix) – a quantum state.
• base (int) – the base of the logarithm [Default: 2].

Returns

The von-Neumann entropy S(rho).

Return type

float

Raises

QiskitError – if the input state is not a valid QuantumState.