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.