Finalize switch to PEP 585 style type annotations (#7367)

Clean up used of old-style type names in docstrings and notebooks.
Remove unused imports and define necessary annotation types for doctest.

Related to #7339

Author: pavoljuhas

cirq-core/cirq/circuits/circuit.py

@@ -918,7 +918,7 @@ def _has_op_at(self, moment_index: int, qubits: Iterable[cirq.Qid]) -> bool:
     def all_qubits(self) -> frozenset[cirq.Qid]:
         """Returns the qubits acted upon by Operations in this circuit.
 
-        Returns: FrozenSet of `cirq.Qid` objects acted on by all operations
+        Returns: frozenset of `cirq.Qid` objects acted on by all operations
             in this circuit.
         """
         return frozenset(q for m in self.moments for q in m.qubits)
@@ -966,15 +966,15 @@ def all_measurement_key_objs(self) -> frozenset[cirq.MeasurementKey]:
     def _measurement_key_objs_(self) -> frozenset[cirq.MeasurementKey]:
         """Returns the set of all measurement keys in this circuit.
 
-        Returns: FrozenSet of `cirq.MeasurementKey` objects that are
+        Returns: frozenset of `cirq.MeasurementKey` objects that are
             in this circuit.
         """
         return self.all_measurement_key_objs()
 
     def all_measurement_key_names(self) -> frozenset[str]:
         """Returns the set of all measurement key names in this circuit.
 
-        Returns: FrozenSet of strings that are the measurement key
+        Returns: frozenset of strings that are the measurement key
             names in this circuit.
         """
         return frozenset(

cirq-core/cirq/linalg/decompositions.py

@@ -116,7 +116,7 @@ def unitary_eig(
             was unitary.
 
     Returns:
-        A Tuple of
+        A tuple of
             eigvals: The eigenvalues of `matrix`.
             V: The unitary matrix with the eigenvectors as columns.
 

cirq-core/cirq/ops/arithmetic_operation.py

@@ -44,21 +44,21 @@ class ArithmeticGate(Gate, metaclass=abc.ABCMeta):
     >>> class Add(cirq.ArithmeticGate):
     ...     def __init__(
     ...         self,
-    ...         target_register: '[int, Sequence[int]]',
-    ...         input_register: 'Union[int, Sequence[int]]',
+    ...         target_register: int | Sequence[int],
+    ...         input_register: int | Sequence[int],
     ...     ):
     ...         self.target_register = target_register
     ...         self.input_register = input_register
     ...
-    ...     def registers(self) -> 'Sequence[Union[int, Sequence[int]]]':
+    ...     def registers(self) -> Sequence[int | Sequence[int]]:
     ...         return self.target_register, self.input_register
     ...
     ...     def with_registers(
-    ...         self, *new_registers: 'Union[int, Sequence[int]]'
+    ...         self, *new_registers: int | Sequence[int]
     ...     ) -> 'Add':
     ...         return Add(*new_registers)
     ...
-    ...     def apply(self, *register_values: int) -> 'Union[int, Iterable[int]]':
+    ...     def apply(self, *register_values: int) -> int | Iterable[int]:
     ...         return sum(register_values)
     >>> cirq.unitary(
     ...     Add(target_register=[2, 2],

cirq-core/cirq/ops/op_tree.py

@@ -40,7 +40,7 @@
     - A list of operations (a `list[cirq.Operation]`).
     - A list of lists of operations (a `list[list[cirq.Operation]]`).
     - A list mixing operations and generators of operations
-        (a `list[Union[cirq.Operation, Iterator[cirq.Operation]]]`).
+        (a `list[cirq.Operation | Iterator[cirq.Operation]]`).
     - Generally anything that can be iterated, and its items iterated, and
         so forth recursively until a bottom layer of operations is found.
     """,

cirq-core/cirq/ops/raw_types.py

@@ -449,7 +449,7 @@ def _default_shape_from_num_qubits(self) -> tuple[int, ...]:
 
     @value.alternative(requires='_num_qubits_', implementation=_default_shape_from_num_qubits)
     def _qid_shape_(self) -> tuple[int, ...]:
-        """Returns a Tuple containing the number of quantum levels of each qid
+        """Returns a tuple containing the number of quantum levels of each qid
         the gate acts on.  E.g. (2, 2, 2) for the three-qubit CCZ gate and
         (3, 3) for a 2-qutrit ternary gate.
         """