diff --git a/src/qibotn/QiboCircuitConvertor.py b/src/qibotn/QiboCircuitConvertor.py
index 694f545..b77aefa 100644
--- a/src/qibotn/QiboCircuitConvertor.py
+++ b/src/qibotn/QiboCircuitConvertor.py
@@ -21,7 +21,7 @@ class QiboCircuitToEinsum:
             """This function is to modify the shape of the tensor to the required format by cuQuantum
             (qubit_states,) * input_output * qubits_involved
             """
-            return (2,) * 2 * nqubits
+            return (2, 2) * nqubits
 
         self.backend = cp
         self.dtype = getattr(self.backend, dtype)
diff --git a/src/qibotn/cutn.py b/src/qibotn/cutn.py
index 6deb078..e6f3e8c 100644
--- a/src/qibotn/cutn.py
+++ b/src/qibotn/cutn.py
@@ -5,6 +5,4 @@ from cuquantum import contract
 
 def eval(qibo_circ, datatype):
     myconvertor = QiboCircuitToEinsum(qibo_circ, dtype=datatype)
-    operands_expression = myconvertor.state_vector_operands()
-    results = contract(*operands_expression)
-    return results
+    return contract(*myconvertor.state_vector_operands())