<s>
In	O
quantum	B-Architecture
computation	I-Architecture
,	O
the	O
Hadamard	B-Device
test	I-Device
is	O
a	O
method	O
used	O
to	O
create	O
a	O
random	O
variable	O
whose	O
expected	O
value	O
is	O
the	O
expected	O
real	O
part	O
,	O
where	O
is	O
a	O
quantum	O
state	O
and	O
is	O
a	O
unitary	B-Application
gate	I-Application
acting	O
on	O
the	O
space	O
of	O
.	O
</s>
<s>
The	O
Hadamard	B-Device
test	I-Device
produces	O
a	O
random	O
variable	O
whose	O
image	O
is	O
in	O
and	O
whose	O
expected	O
value	O
is	O
exactly	O
.	O
</s>
<s>
To	O
perform	O
the	O
Hadamard	B-Device
test	I-Device
we	O
first	O
calculate	O
the	O
state	O
.	O
</s>
<s>
The	O
Hadamard	B-Device
test	I-Device
has	O
many	O
applications	O
in	O
quantum	B-Device
algorithms	I-Device
such	O
as	O
the	O
Aharonov-Jones-Landau	B-Algorithm
algorithm	I-Algorithm
.	O
</s>
