qiskit.quantum_info.DensityMatrix.to_statevector¶
-
DensityMatrix.to_statevector(atol=None, rtol=None)[source]¶ Return a statevector from a pure density matrix.
- Parameters
atol (float) – Absolute tolerance for checking operation validity.
rtol (float) – Relative tolerance for checking operation validity.
- Returns
- The pure density matrix’s corresponding statevector.
Corresponds to the eigenvector of the only non-zero eigenvalue.
- Return type
- Raises
QiskitError – if the state is not pure.