def default(
num_qubits: Optional[int] = None,
*,
qid_shape: Optional[Tuple[int, ...]] = None) -> 'ApplyUnitaryArgs':
"""A default instance starting in state |0⟩.
Specify exactly one argument.
Args:
num_qubits: The number of qubits to make space for in the state.
qid_shape: The shape of the state, specifying the dimension of each
qid.
Raises:
TypeError: If exactly neither `num_qubits` or `qid_shape` is provided or
both are provided.
"""
if (num_qubits is None) == (qid_shape is None):
raise TypeError('Specify exactly one of num_qubits or qid_shape.')
if num_qubits is not None:
qid_shape = (2, ) * num_qubits
qid_shape = cast(Tuple[int, ...], qid_shape) # Satisfy mypy
num_qubits = len(qid_shape)
state = qis.one_hot(index=(0, ) * num_qubits,
shape=qid_shape,
dtype=np.complex128)
return ApplyUnitaryArgs(state, np.empty_like(state), range(num_qubits))
def _strat_has_unitary_from_apply_unitary(val: Any) -> Optional[bool]:
"""Attempts to infer a value's unitary-ness via its _apply_unitary_ method."""
method = getattr(val, '_apply_unitary_', None)
if method is None:
return None
val_qid_shape = qid_shape_protocol.qid_shape(val, None)
if val_qid_shape is None:
return None
state = qis.one_hot(shape=val_qid_shape, dtype=np.complex64)
buffer = np.empty_like(state)
result = method(ApplyUnitaryArgs(state, buffer, range(len(val_qid_shape))))
if result is NotImplemented:
return None
return result is not None