Delete references to the removed QubitStateVector class (#203)

* remove qsv and update changelog

* ran black

* Update CHANGELOG.md

Co-authored-by: Mudit Pandey <[email protected]>

* Update pennylane_cirq/cirq_device.py

Co-authored-by: Mudit Pandey <[email protected]>

* replace qubit_state_vector -> state_prep

* ran black

---------

Co-authored-by: Mudit Pandey <[email protected]>

Author: andrijapau

CHANGELOG.md

@@ -6,6 +6,9 @@
 
 ### Breaking changes 💔
 
+* The ``qml.QubitStateVector`` template has been removed. Instead, use :class:`~pennylane.StatePrep`.
+  [(#203)](https://github.com/PennyLaneAI/pennylane-cirq/pull/203)
+
 ### Deprecations 👋
 
 ### Documentation 📝
@@ -16,6 +19,8 @@
 
 This release contains contributions from (in alphabetical order):
 
+Andrija Paurevic
+
 ---
 # Release 0.39.0
 

doc/devices/qsim.rst

@@ -122,7 +122,7 @@ more qubits.
 For state preparation qsim relies on decomposing ``BasisState`` into a set of
 `PauliX
 <https://pennylane.readthedocs.io/en/stable/code/api/pennylane.PauliX.html>`__
-gates and `QubitStateVector
-<https://pennylane.readthedocs.io/en/stable/code/api/pennylane.QubitStateVector.html>`__
+gates and `StatePrep
+<https://pennylane.readthedocs.io/en/stable/code/api/pennylane.StatePrep.html>`__
 via `Möttönen state preparation
 <https://pennylane.readthedocs.io/en/stable/code/api/pennylane.templates.state_preparations.MottonenStatePreparation.html>`__.

pennylane_cirq/cirq_device.py

@@ -118,7 +118,6 @@ def __init__(self, wires, shots, qubits=None):
     _base_operation_map = {
         **{f"Pow({k})": v for k, v in _pow_operation_map.items()},
         "BasisState": None,
-        "QubitStateVector": None,
         "StatePrep": None,
         "QubitUnitary": CirqOperation(cirq.MatrixGate),
         "PauliX": CirqOperation(lambda: cirq.X),
@@ -240,11 +239,11 @@ def _apply_basis_state(self, basis_state_operation):
         raise NotImplementedError
 
     @abc.abstractmethod
-    def _apply_qubit_state_vector(self, qubit_state_vector_operation):
+    def _apply_state_prep(self, state_prep_operation):
         """Apply a state vector preparation.
 
         Args:
-            qubit_state_vector_operation (pennylane.QubitStateVector): the QubitStateVector operation instance that shall be applied
+            state_prep_operation (pennylane.StatePrep): the StatePrep operation instance that shall be applied
 
         Raises:
             NotImplementedError: when not implemented in the subclass
@@ -277,15 +276,15 @@ def apply(self, operations, **kwargs):
         rotations = kwargs.pop("rotations", [])
 
         for i, operation in enumerate(operations):
-            if i > 0 and operation.name in {"BasisState", "QubitStateVector", "StatePrep"}:
+            if i > 0 and operation.name in {"BasisState", "StatePrep"}:
                 raise qml.DeviceError(
                     f"The operation {operation.name} is only supported at the beginning of a circuit."
                 )
 
             if operation.name == "BasisState":
                 self._apply_basis_state(operation)
-            elif operation.name in {"StatePrep", "QubitStateVector"}:
-                self._apply_qubit_state_vector(operation)
+            elif operation.name == "StatePrep":
+                self._apply_state_prep(operation)
             else:
                 self._apply_operation(operation)
 

pennylane_cirq/qsim_device.py

@@ -67,7 +67,6 @@ def reset(self):
     def operations(self):
         # pylint: disable=missing-function-docstring
         return set(self._base_operation_map) - {
-            "QubitStateVector",
             "StatePrep",
             "BasisState",
             "CRX",
@@ -129,7 +128,6 @@ def __init__(self, wires, qsimh_options, shots=None, qubits=None):
     def operations(self):
         # pylint: disable=missing-function-docstring
         return set(self._base_operation_map) - {
-            "QubitStateVector",
             "StatePrep",
             "BasisState",
             "CRX",

pennylane_cirq/simulator_device.py

@@ -91,16 +91,12 @@ def _apply_basis_state(self, basis_state_operation):
 
         self._initial_state = basis_state_operation.state_vector(wire_order=self.wires).flatten()
 
-    def _apply_qubit_state_vector(self, qubit_state_vector_operation):
+    def _apply_state_prep(self, state_prep_operation):
         # pylint: disable=missing-function-docstring
         if self.shots is not None:
-            raise qml.DeviceError(
-                "The operations StatePrep and QubitStateVector are only supported in analytic mode."
-            )
+            raise qml.DeviceError("The operator StatePrep is only supported in analytic mode.")
 
-        self._initial_state = qubit_state_vector_operation.state_vector(
-            wire_order=self.wires
-        ).flatten()
+        self._initial_state = state_prep_operation.state_vector(wire_order=self.wires).flatten()
 
     def apply(self, operations, **kwargs):
         # pylint: disable=missing-function-docstring
@@ -272,8 +268,8 @@ def _apply_basis_state(self, basis_state_operation):
         super()._apply_basis_state(basis_state_operation)
         self._initial_state = self._convert_to_density_matrix(self._initial_state)
 
-    def _apply_qubit_state_vector(self, qubit_state_vector_operation):
-        super()._apply_qubit_state_vector(qubit_state_vector_operation)
+    def _apply_state_prep(self, state_prep_operation):
+        super()._apply_state_prep(state_prep_operation)
         self._initial_state = self._convert_to_density_matrix(self._initial_state)
 
     def _convert_to_density_matrix(self, state_vec):

tests/test_apply.py

@@ -106,7 +106,7 @@ def test_basis_state(self, shots, tol, state):
         expected[np.ravel_multi_index(state, [2] * 4)] = 1
         assert np.allclose(res, expected, **tol)
 
-    def test_qubit_state_vector(self, init_state, shots, tol):
+    def test_state_prep(self, init_state, shots, tol):
         """Test PauliX application"""
         dev = SimulatorDevice(1, shots=shots)
         state = init_state(1)
@@ -288,7 +288,7 @@ def test_identity_basis_state(self, shots, tol):
         expected = np.kron(expected, expected.conj()).reshape([16, 16])
         assert np.allclose(res, expected, **tol)
 
-    def test_qubit_state_vector(self, init_state, shots, tol):
+    def test_state_prep(self, init_state, shots, tol):
         """Test PauliX application"""
         dev = MixedStateSimulatorDevice(1, shots=shots)
         state = init_state(1)

tests/test_mixed_simulator_device.py

@@ -445,7 +445,7 @@ def test_basis_state_not_at_beginning_error(self, simulator_device_1_wire):
         ):
             simulator_device_1_wire.apply([qml.PauliX(0), qml.BasisState(np.array([0]), wires=[0])])
 
-    def test_qubit_state_vector_not_at_beginning_error(self, simulator_device_1_wire):
+    def test_state_prep_not_at_beginning_error(self, simulator_device_1_wire):
         """Tests that application of StatePrep raises an error if is not
         the first operation."""
 
@@ -474,15 +474,15 @@ def test_basis_state_not_analytic_error(self, simulator_device_1_wire):
         ):
             simulator_device_1_wire.apply([qml.BasisState(np.array([0]), wires=[0])])
 
-    def test_qubit_state_vector_not_analytic_error(self, simulator_device_1_wire):
+    def test_state_prep_not_analytic_error(self, simulator_device_1_wire):
         """Tests that application of StatePrep raises an error if the device
         is not in analytic mode."""
 
         simulator_device_1_wire.reset()
 
         with pytest.raises(
             qml.DeviceError,
-            match="The operations StatePrep and QubitStateVector are only supported in analytic mode.",
+            match="The operator StatePrep is only supported in analytic mode.",
         ):
             simulator_device_1_wire.apply([qml.StatePrep(np.array([0, 1]), wires=[0])])
 

tests/test_simulator_device.py

@@ -471,7 +471,7 @@ def test_basis_state_not_at_beginning_error(self, simulator_device_1_wire):
         ):
             simulator_device_1_wire.apply([qml.PauliX(0), qml.BasisState(np.array([0]), wires=[0])])
 
-    def test_qubit_state_vector_not_at_beginning_error(self, simulator_device_1_wire):
+    def test_state_prep_not_at_beginning_error(self, simulator_device_1_wire):
         """Tests that application of StatePrep raises an error if is not
         the first operation."""
 
@@ -500,15 +500,15 @@ def test_basis_state_not_analytic_error(self, simulator_device_1_wire):
         ):
             simulator_device_1_wire.apply([qml.BasisState(np.array([0]), wires=[0])])
 
-    def test_qubit_state_vector_not_analytic_error(self, simulator_device_1_wire):
+    def test_state_prep_not_analytic_error(self, simulator_device_1_wire):
         """Tests that application of StatePrep raises an error if the device
         is not in analytic mode."""
 
         simulator_device_1_wire.reset()
 
         with pytest.raises(
             qml.DeviceError,
-            match="The operations StatePrep and QubitStateVector are only supported in analytic mode.",
+            match="The operator StatePrep is only supported in analytic mode.",
         ):
             simulator_device_1_wire.apply([qml.StatePrep(np.array([0, 1]), wires=[0])])