Ex10 3

$\def\abs#1{|#1|}\def\i{\mathbf {i}}\def\ket#1{|{#1}\rangle}\def\bra#1{\langle{#1}|}\def\braket#1#2{\langle{#1}|{#2}\rangle}\def\tr{\mathord{\mbox{tr}}}\mathbf{Exercise\ 10.3}$

a) Find the density operators for the whole system and both qubits of $\ket{\Psi^-} =\frac{1}{\sqrt{2}}(\ket{00} - \ket{11})$.

b) Find the density operators for the whole system and both qubits of $\ket{\Phi^+} = \frac{1}{\sqrt{2}}(\ket{01} + \ket{10})$.