def __init__(self, matrix: np.ndarray, display_name: str = "Hermitian"):
"""
Args:
matrix (numpy.ndarray): Hermitian matrix that defines the observable.
display_name (str): Name to use for an instance of this Hermitian matrix
observable for circuit diagrams. Defaults to `Hermitian`.
Raises:
ValueError: If `matrix` is not a two-dimensional square matrix,
or has a dimension length that is not a positive power of 2,
or is not Hermitian.
Examples:
>>> Observable.Hermitian(matrix=np.array([[0, 1],[1, 0]]))
"""
verify_quantum_operator_matrix_dimensions(matrix)
self._matrix = np.array(matrix, dtype=complex)
if not is_hermitian(self._matrix):
raise ValueError(f"{self._matrix} is not hermitian")
qubit_count = int(np.log2(self._matrix.shape[0]))
eigendecomposition = Hermitian._get_eigendecomposition(self._matrix)
self._eigenvalues = eigendecomposition["eigenvalues"]
self._diagonalizing_gates = (Gate.Unitary(
matrix=eigendecomposition["eigenvectors"].conj().T), )
super().__init__(qubit_count=qubit_count,
ascii_symbols=[display_name] * qubit_count)
def test_is_hermitian_exception():
is_hermitian(invalid_matrix_type_error)
def test_is_hermitian_false(matrix):
assert not is_hermitian(matrix)
def test_is_hermitian_true():
assert is_hermitian(valid_unitary_hermitian_matrix)
