forgot a 2

elements/main.py

@@ -50,9 +50,9 @@ class BeamSplitter(Element):
         self.output_vector = self.matrix @ input_state
 
         if side == "left":
-            ans, _ = np.split(self.output_vector)
+            ans, _ = np.split(self.output_vector, 2)
 
         elif side == "right":
-            _, ans = np.split(self.output_vector)
+            _, ans = np.split(self.output_vector, 2)
 
         return ans