style fix

pennylane_lightning/lightning_qubit/_state_vector.py

@@ -76,6 +76,11 @@ def state(self):
         state = np.zeros(2**self._num_wires, dtype=self.dtype)
         self._qubit_state.getState(state)
         return state
+
+    def update_num_qubits(self, new_num_wires: int):
+        self._num_wires = new_num_wires
+        self._qubit_state.updateNumQubits(new_num_wires)
+        self.reset_state()
 
     def _state_dtype(self):
         """Binding to Lightning Managed state vector C++ class.
@@ -84,11 +89,6 @@ def _state_dtype(self):
         """
         return StateVectorC128 if self.dtype == np.complex128 else StateVectorC64
 
-    def _update_num_qubits(self, new_num_wires: int):
-        self._num_wires = new_num_wires
-        self._qubit_state.updateNumQubits(new_num_wires)
-        self.reset_state()
-
     def _apply_state_vector(self, state, device_wires: Wires):
         """Initialize the internal state vector in a specified state.
         Args:

pennylane_lightning/lightning_qubit/lightning_qubit.py

@@ -404,7 +404,7 @@ def execute(
                     circuit = circuit.map_to_standard_wires()
             else:
                 if not self.wires:
-                    self._statevector._update_num_qubits(circuit.num_wires)
+                    self._statevector.update_num_qubits(circuit.num_wires)
                     circuit = circuit.map_to_standard_wires()
 
             if self._wire_map is not None:

tests/lightning_qubit/test_state_vector_class.py

@@ -485,39 +485,21 @@ def test_get_final_state(tol, operation, input, expected_output, par):
     assert final_state == state_vector
 
 
-def test_dynamically_allocate_qubit(tol, operation, input, expected_output, par):
-    """Tests that applying an operation yields the expected output state for two wire
-    operations that have parameters."""
-    if device_name != "lightning.qubit":
-        pytest.skip("Only Lightning Qubit allows dynamic qubit allocation", allow_module_level=True)
-
-    wires = 2
-    state_vector = LightningStateVector(wires)
-    tape = QuantumScript(
-        [qml.StatePrep(np.array(input), Wires(range(wires))), operation(*par, Wires(range(wires)))]
-    )
-    final_state = state_vector.get_final_state(tape)
-
-    assert np.allclose(final_state.state, np.array(expected_output), atol=tol, rtol=0)
-    assert final_state.state.dtype == final_state.dtype
-    assert final_state == state_vector
-
-
 @pytest.mark.parametrize("num_wires", range(2, 5))
 @pytest.mark.parametrize("dtype", [np.complex64, np.complex128])
 def test_update_num_qubit(num_wires, dtype):
-    """ """
+    """Tests that the state vector is correctly updated when the number of qubits is changed."""
     if device_name != "lightning.qubit":
         pytest.skip("Only Lightning Qubit allows dynamic qubit allocation")
 
     state_vector = LightningStateVector(num_wires, dtype=dtype)
 
-    state_vector._update_num_qubits(num_wires + 2)
+    state_vector.update_num_qubits(num_wires + 2)
     expected_output = np.zeros(2 ** (num_wires + 2), dtype=dtype)
     expected_output[0] = 1
     assert np.allclose(state_vector.state, expected_output)
 
-    state_vector._update_num_qubits(num_wires - 1)
+    state_vector.update_num_qubits(num_wires - 1)
     expected_output = np.zeros(2 ** (num_wires - 1), dtype=dtype)
     expected_output[0] = 1
     assert np.allclose(state_vector.state, expected_output)