|q⟩
Bad Qubits
Play
Quest
Questions
Learn
Playground
☕
← Question Bank
Multiple choice
The parameter-shift rule estimates a gradient as
0.5
(
f
(
θ
+
π
/
2
)
−
f
(
θ
−
π
/
2
)
)
0.5 ( f(\theta + \pi/2) - f(\theta - \pi/2) )
0.5
(
f
(
θ
+
π
/2
)
−
f
(
θ
−
π
/2
))
, where here
f
(
θ
)
=
cos
(
θ
)
f(\theta) = \cos(\theta)
f
(
θ
)
=
cos
(
θ
)
. At
θ
=
π
/
4
\theta = \pi/4
θ
=
π
/4
, what value does it give?
−
0.5
-0.5
−
0.5
−
2
/
2
≈
−
0.707
-\sqrt{2}/2 \approx -0.707
−
2
/2
≈
−
0.707
+
2
/
2
≈
+
0.707
+\sqrt{2}/2 \approx +0.707
+
2
/2
≈
+
0.707
−
1.0
-1.0
−
1.0
Check answer