purity¶
- purity(state, validate=True)[source]¶
Calculate the purity of a quantum state.
The purity of a density matrix \(\rho\) is
..code:
text{Purity}(rho) = Tr[rho^2]
- Parameters
state (Statevector or DensityMatrix) – a quantum state.
validate (bool) – check if input state is valid [Default: True]
- Returns
the purity \(\Tr[\rho^2]\).
- Return type
float
- Raises
QiskitError – if the input isn’t a valid quantum state.