@@ -30,6 +30,19 @@ __all__ = [

 def apply(gate, qubits, state):

+    """Apply a gate to the specified qubits of a state

+

+    Parameters

+    ----------

+    gate : ndarray[complex]

+    qubits : sequence of int

+        The qubits on which to act. Qubit 0 is the least significant qubit.

+    state : ndarray[complex]

+

+    Returns

+    -------

+    new_state : ndarray[complex]

+    """

     n_gate_qubits = gate.shape[0].bit_length() - 1

     n_state_qubits = state.shape[0].bit_length() - 1

     assert len(qubits) == n_gate_qubits