Ex10 15

$\def\abs#1{|#1|}\def\i{\mathbf {i}}\def\ket#1{|{#1}\rangle}\def\bra#1{\langle{#1}|}\def\braket#1#2{\langle{#1}|{#2}\rangle}\def\tr{\mathord{\mbox{tr}}}\mathbf{Exercise\ 10.15}$

a) Show that any two-qubit state can be converted to $\ket{00}$ via LOCC.

b) Show that any $n$-qubit state can be converted to a state unentangled with respect to the tensor decomposition into the $n$ qubits.