def _scan_single_qubit_ops(
circuit: Circuit, index: Optional[int],
qubit: ops.QubitId) -> Tuple[List[int], List[ops.Operation]]:
operations = [] # type: List[ops.Operation]
indices = [] # type: List[int]
while index is not None:
op = cast(ops.Operation, circuit.operation_at(qubit, index))
if len(op.qubits) != 1 or protocols.unitary(op, None) is None:
break
indices.append(index)
operations.append(op)
index = circuit.next_moment_operating_on([qubit], index + 1)
return indices, operations
def _scan_two_qubit_ops_into_matrix(
self,
circuit: Circuit,
index: Optional[int],
qubits: Tuple[ops.QubitId, ...]
) -> Tuple[List[ops.Operation], List[int], np.ndarray]:
"""Accumulates operations affecting the given pair of qubits.
The scan terminates when it hits the end of the circuit, finds an
operation without a known matrix, or finds an operation that interacts
the given qubits with other qubits.
Args:
circuit: The circuit to scan for operations.
index: The index to start scanning forward from.
qubits: The pair of qubits we care about.
Returns:
A tuple containing:
0. The operations.
1. The moment indices those operations were on.
2. A matrix equivalent to the effect of the scanned operations.
"""
product = np.eye(4, dtype=np.complex128)
all_operations = []
touched_indices = []
while index is not None:
operations = list({circuit.operation_at(q, index) for q in qubits})
op_data = [
self._op_to_matrix(op, qubits)
for op in operations
if op is not None
]
# Stop at any non-constant or non-local interaction.
if any(e is None for e in op_data):
break
present_ops = [op for op in operations if op]
present_op_data = cast(List[np.ndarray], op_data)
for op_mat in present_op_data:
product = np.dot(op_mat, product)
all_operations.extend(present_ops)
touched_indices.append(index)
index = circuit.next_moment_operating_on(qubits, index + 1)
return all_operations, touched_indices, product
def _scan_single_qubit_ops(
self, circuit: Circuit, index: Optional[int],
qubit: ops.QubitId) -> Tuple[List[int], List[ops.KnownMatrix]]:
operations = [] # type: List[ops.KnownMatrix]
indices = [] # type: List[int]
while index is not None:
op = cast(ops.Operation, circuit.operation_at(qubit, index))
if len(op.qubits) != 1:
break
operation = self.extensions.try_cast(ops.KnownMatrix, op)
if operation is None:
break
indices.append(index)
operations.append(operation)
index = circuit.next_moment_operating_on([qubit], index + 1)
return indices, operations
def test_operation_at():
a = cirq.QubitId()
b = cirq.QubitId()
c = Circuit()
assert c.operation_at(a, 0) is None
assert c.operation_at(a, -1) is None
assert c.operation_at(a, 102) is None
c = Circuit([Moment()])
assert c.operation_at(a, 0) is None
c = Circuit([Moment([cirq.X(a)])])
assert c.operation_at(b, 0) is None
assert c.operation_at(a, 1) is None
assert c.operation_at(a, 0) == cirq.X(a)
c = Circuit([Moment(), Moment([cirq.CZ(a, b)])])
assert c.operation_at(a, 0) is None
assert c.operation_at(a, 1) == cirq.CZ(a, b)
