def _add_unitary_single(self, gate, qubit):
<EOL>indexes = einsum_vecmul_index([qubit], self._number_of_qubits)<EOL>gate_tensor = np.array(gate, dtype=complex)<EOL>self._statevector = np.einsum(indexes, gate_tensor,<EOL>self._statevector,<EOL>dtype=complex,<EOL>casting='<STR_LIT>')<EOL>
Apply an arbitrary 1-qubit unitary matrix.

        Args:
            gate (matrix_like): a single qubit gate matrix
            qubit (int): the qubit to apply gate to