Update qiskit_dynamics/signals/signals.py

Co-authored-by: Daniel Puzzuoli <[email protected]>

qiskit_dynamics/signals/signals.py

@@ -644,7 +644,7 @@ def __init__(
 
         samples = unp.asarray(samples)
         if carrier_freq is None:
-            carrier_freq = unp.zeros(samples.shape[-1], dtype=float)
+            carrier_freq = np.zeros(samples.shape[-1], dtype=float)
 
         if phase is None:
             phase = unp.zeros(samples.shape[-1], dtype=float)