def assert_pauli_expansion_is_consistent_with_unitary(val: Any) -> None:
"""Checks Pauli expansion against unitary matrix."""
# Check to see if the protocol is supported without doing a fallback
# to unitary, otherwise the test is vacuous.
method = getattr(val, '_pauli_expansion_', None)
if method is None:
return
pauli_expansion = protocols.pauli_expansion(val, default=None)
if pauli_expansion is None:
return
unitary = protocols.unitary(val, None)
if unitary is None:
return
num_qubits = protocols.num_qubits(val,
default=unitary.shape[0].bit_length() -
1)
basis = operator_spaces.kron_bases(operator_spaces.PAULI_BASIS,
repeat=num_qubits)
recovered_unitary = operator_spaces.matrix_from_basis_coefficients(
pauli_expansion, basis)
assert np.allclose(unitary, recovered_unitary, rtol=0, atol=1e-12)
def pauli_expansion(
val: Any,
*,
default: Union[value.LinearDict[str],
TDefault] = RaiseTypeErrorIfNotProvided,
atol: float = 1e-9) -> Union[value.LinearDict[str], TDefault]:
"""Returns coefficients of the expansion of val in the Pauli basis.
Args:
val: The value whose Pauli expansion is to returned.
default: Determines what happens when `val` does not have methods that
allow Pauli expansion to be obtained (see below). If set, the value
is returned in that case. Otherwise, TypeError is raised.
atol: Ignore coefficients whose absolute value is smaller than this.
Returns:
If `val` has a _pauli_expansion_ method, then its result is returned.
Otherwise, if `val` has a small unitary then that unitary is expanded
in the Pauli basis and coefficients are returned. Otherwise, if default
is set to None or other value then default is returned. Otherwise,
TypeError is raised.
Raises:
TypeError if `val` has none of the methods necessary to obtain its Pauli
expansion and no default value has been provided.
"""
method = getattr(val, '_pauli_expansion_', None)
expansion = NotImplemented if method is None else method()
if expansion is not NotImplemented:
return expansion.clean(atol=atol)
# Don't attempt to derive the pauli expansion if this is a qudit gate
if not all(d == 2 for d in qid_shape_protocol.qid_shape(val, default=())):
if default is RaiseTypeErrorIfNotProvided:
raise TypeError(
'No Pauli expansion for object {} of type {}'.format(
val, type(val)))
return default
matrix = unitary(val, default=None)
if matrix is None:
if default is RaiseTypeErrorIfNotProvided:
raise TypeError(
'No Pauli expansion for object {} of type {}'.format(
val, type(val)))
return default
num_qubits = matrix.shape[0].bit_length() - 1
basis = operator_spaces.kron_bases(operator_spaces.PAULI_BASIS,
repeat=num_qubits)
expansion = operator_spaces.expand_matrix_in_orthogonal_basis(
matrix, basis)
return expansion.clean(atol=atol)
def pauli_expansion(val: Any,
*,
default: Optional[Dict[
str, complex]] = RaiseTypeErrorIfNotProvided,
tolerance: float = 1e-9) -> Optional[Dict[str, complex]]:
"""Returns coefficients of the expansion of val in the Pauli basis.
Args:
val: The value whose Pauli expansion is to returned.
default: Determines what happens when `val` does not have methods that
allow Pauli expansion to be obtained (see below). If set, the value
is returned in that case. Otherwise, TypeError is raised.
tolerance: Ignore coefficients whose absolute value is smaller than
this.
Returns:
If `val` has a _pauli_expansion_ method, then its result is returned.
Otherwise, if `val` has a small unitary then that unitary is expanded
in the Pauli basis and coefficients are returned. Otherwise, if default
is set to None or other value then default is returned. Otherwise,
TypeError is raised.
Raises:
TypeError if `val` has none of the methods necessary to obtain its Pauli
expansion and no default value has been provided.
"""
method = getattr(val, '_pauli_expansion_', None)
expansion = NotImplemented if method is None else method()
if expansion is not NotImplemented:
return _filter_coefficients(expansion, tolerance)
matrix = unitary(val, default=None)
if matrix is None:
if default is RaiseTypeErrorIfNotProvided:
raise TypeError(
'No Pauli expansion for object {} of type {}'.format(
val, type(val)))
return default
num_qubits = matrix.shape[0].bit_length() - 1
basis = operator_spaces.kron_bases(operator_spaces.PAULI_BASIS,
repeat=num_qubits)
expansion = operator_spaces.expand_matrix_in_orthogonal_basis(
matrix, basis)
return _filter_coefficients(expansion, tolerance)
def assert_pauli_expansion_is_consistent_with_unitary(val: Any) -> None:
"""Checks Pauli expansion against unitary matrix."""
pauli_expansion = protocols.pauli_expansion(val, default=None)
if pauli_expansion is None:
return
unitary = protocols.unitary(val, None)
if unitary is None:
return
num_qubits = unitary.shape[0].bit_length() - 1
basis = operator_spaces.kron_bases(operator_spaces.PAULI_BASIS,
repeat=num_qubits)
recovered_unitary = operator_spaces.matrix_from_basis_coefficients(
pauli_expansion, basis)
assert np.allclose(unitary, recovered_unitary, rtol=0, atol=1e-12)