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For the pure two-qubit state
∣
ψ
⟩
=
cos
(
θ
)
∣
00
⟩
+
sin
(
θ
)
∣
11
⟩
|\psi\rangle = \cos(\theta)|00\rangle + \sin(\theta)|11\rangle
∣
ψ
⟩
=
cos
(
θ
)
∣00
⟩
+
sin
(
θ
)
∣11
⟩
with real amplitudes and
θ
=
π
/
5
\theta = \pi/5
θ
=
π
/5
, the concurrence is
C
=
2
∣
a
d
−
b
c
∣
C = 2|ad - bc|
C
=
2∣
a
d
−
b
c
∣
where
(
a
,
b
,
c
,
d
)
(a,b,c,d)
(
a
,
b
,
c
,
d
)
are the amplitudes of
(
∣
00
⟩
,
∣
01
⟩
,
∣
10
⟩
,
∣
11
⟩
)
(|00\rangle,|01\rangle,|10\rangle,|11\rangle)
(
∣00
⟩
,
∣01
⟩
,
∣10
⟩
,
∣11
⟩)
, reducing to
C
=
∣
sin
(
2
θ
)
∣
C = |\sin(2\theta)|
C
=
∣
sin
(
2
θ
)
∣
. What is
C
C
C
?
🔬 try it before you answer
0.476
0.309
0.951
0.588
Check answer