Enable proper iteration over Statevector

qiskit/quantum_info/states/statevector.py

@@ -218,6 +218,9 @@ def __getitem__(self, key):
         else:
             raise QiskitError("Key must be int or a valid binary string.")
 
+    def __iter__(self):
+        yield from self._data
+
     @property
     def data(self):
         """Return data."""

test/python/quantum_info/states/test_statevector.py

@@ -1164,6 +1164,19 @@ def test_statevector_draw_latex_regression(self):
         self.assertTrue(latex_string.startswith(" |0\\rangle"))
         self.assertNotIn("|1\\rangle", latex_string)
 
+    def test_statevctor_iter(self):
+        """Test iteration over a state vector"""
+        empty_vector = []
+        dummy_vector = [1, 2, 3]
+        empty_sv = Statevector([])
+        sv = Statevector(dummy_vector)
+
+        # Assert that successive iterations behave as expected, i.e., the
+        # iterator is reset upon each exhaustion of the corresponding
+        # collection of elements.
+        for _ in range(2):
+            self.assertEqual(empty_vector, [x for x in empty_sv])
+            self.assertEqual(dummy_vector, [x for x in sv])
 
 if __name__ == "__main__":
     unittest.main()