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Multiple choice
An amplitude-damping channel with
g
=
0.5
g = 0.5
g
=
0.5
acts on
ρ
=
∣
+
⟩
⟨
+
∣
=
[
0.5
0.5
0.5
0.5
]
\rho = |+\rangle\langle +| = \begin{bmatrix}0.5 & 0.5 \\ 0.5 & 0.5\end{bmatrix}
ρ
=
∣
+
⟩
⟨
+
∣
=
[
0.5
0.5
0.5
0.5
]
. What is the purity
t
r
(
E
(
ρ
)
2
)
\mathrm{tr}(E(\rho)^2)
tr
(
E
(
ρ
)
2
)
of the output state?
🔬 try it before you answer
1
0.5
0.875
0.75
Check answer