@@ -38,7 +38,7 @@ def _check_valid_gate(gate):

         and gate.shape[0] == gate.shape[1]

         # has size 2**n, n > 1

         and np.log2(gate.shape[0]).is_integer()

-        and np.log2(gate.shape[0]) > 0

+        and gate.shape[0].bit_length() > 1

         # is unitary

         and np.allclose(gate @ gate.conjugate().transpose(), np.identity(gate.shape[0]))

     ):

@@ -52,9 +52,7 @@ def n_qubits(gate):

     an integer power of 2.

     """

     _check_valid_gate(gate)

-    n = np.log2(gate.shape[0])

-    assert n.is_integer()

-    return int(n)

+    return gate.shape[0].bit_length() - 1

 def controlled(gate):