fix: minor fixes to measurements

src/qibo/backends/clifford.py

@@ -85,8 +85,19 @@ def zero_state(self, nqubits: int):
         symplectic_matrix[nqubits:-1, nqubits : 2 * nqubits] = self.np.copy(I)
         return symplectic_matrix
 
-    def reshape_clifford_state(self, state, nqubits):
-        """Reshape the symplectic matrix to the shape needed by the engine.
+    def clifford_pre_execution_reshape(self, state):
+        """Reshape the symplectic matrix to the shape needed by the engine before circuit execution.
+
+        Args:
+            state (ndarray): The input state.
+
+        Returns:
+            (ndarray): The reshaped state.
+        """
+        return self.engine.clifford_pre_execution_reshape(state)
+
+    def clifford_post_execution_reshape(self, state, nqubits):
+        """Reshape the symplectic matrix to the shape needed by the engine after circuit execution.
 
         Args:
             state (ndarray): The input state.
@@ -95,7 +106,7 @@ def reshape_clifford_state(self, state, nqubits):
         Returns:
             (ndarray): The reshaped state.
         """
-        return self.engine.reshape_clifford_state(state, nqubits)
+        return self.engine.clifford_post_execution_reshape(state, nqubits)
 
     def apply_gate_clifford(self, gate, symplectic_matrix, nqubits):
         operation = getattr(self.clifford_operations, gate.__class__.__name__)
@@ -132,12 +143,12 @@ def execute_circuit(self, circuit, initial_state=None, nshots: int = 1000):
 
             state = self.zero_state(nqubits) if initial_state is None else initial_state
 
-            state = self.reshape_clifford_state(state, nqubits)
+            state = self.clifford_pre_execution_reshape(state)
 
             for gate in circuit.queue:
                 state = gate.apply_clifford(self, state, nqubits)
 
-            state = self.reshape_clifford_state(state, nqubits)
+            state = self.clifford_post_execution_reshape(state, nqubits)
 
             clifford = Clifford(
                 state,
@@ -220,6 +231,8 @@ def sample_shots(
         if isinstance(qubits, list):
             qubits = tuple(qubits)
 
+        state = self.clifford_pre_execution_reshape(state)
+
         if collapse:
             samples = [
                 self.clifford_operations.M(state, qubits, nqubits)

src/qibo/backends/clifford_operations.py

@@ -404,7 +404,7 @@ def _random_outcome(state, p, q, nqubits):
     if h.shape[0] > 0:
         state = _rowsum(
             state,
-            h,
+            h.astype(np.uint),
             p * np.ones(h.shape[0], dtype=np.uint),
             nqubits,
         )

src/qibo/backends/numpy.py

@@ -77,7 +77,10 @@ def to_numpy(self, x):
     def compile(self, func):
         return func
 
-    def reshape_clifford_state(self, state, nqubits):
+    def clifford_pre_execution_reshape(self, state):
+        return state
+
+    def clifford_post_execution_reshape(self, state, nqubits):
         return state
 
     def zero_state(self, nqubits):