Exercise 3.12 Discussion

$\def\i{\mathbf {i}}\def\ket#1{|{#1}\rangle}\def\bra#1{\langle{#1}|}\def\braket#1#2{\langle{#1}|{#2}\rangle}\mathbf{Exercise\ 3.12}$

Give an example of a two-qubit state which is a superposition with respect to the standard basis but which is not entangled.