Merge pull request #862 from qiboteam/probnoisy

add docs to noisy circuit probabilities

src/qibo/states.py

@@ -299,7 +299,11 @@ def __array__(self):
         return self.state(numpy=True)
 
     def probabilities(self, qubits=None):
-        """Calculates measurement probabilities by tracing out qubits.
+        """Calculates measurement probabilities by tracing out qubits. When
+        a noise model is applied to the circuit this method will return the
+        probabilities from the last execution shot, which may or may not
+        correspond to the noise-free state depending on whether the noise was
+        applied or not in that specific execution.
 
         Args:
             qubits (list, set): Set of qubits that are measured.