<s>
The	O
kinetic	B-Algorithm
inductance	I-Algorithm
detector	I-Algorithm
(	O
KID	O
)	O
—	O
also	O
known	O
as	O
a	O
microwave	B-Algorithm
kinetic	I-Algorithm
inductance	I-Algorithm
detector	I-Algorithm
(	O
MKID	B-Algorithm
)	O
—	O
is	O
a	O
type	O
of	O
superconducting	O
photon	B-Application
detector	O
first	O
developed	O
by	O
scientists	O
at	O
the	O
California	O
Institute	O
of	O
Technology	O
and	O
the	O
Jet	O
Propulsion	O
Laboratory	O
in	O
2003	O
.	O
</s>
<s>
These	O
devices	O
operate	O
at	O
cryogenic	B-Algorithm
temperatures	O
,	O
typically	O
below	O
1	O
kelvin	B-Operating_System
.	O
</s>
<s>
They	O
are	O
being	O
developed	O
for	O
high-sensitivity	O
astronomical	O
detection	O
for	O
frequencies	O
ranging	O
from	O
the	O
far-infrared	O
to	O
X-rays	B-Library
.	O
</s>
<s>
Photons	B-Application
incident	O
on	O
a	O
strip	O
of	O
superconducting	O
material	O
break	O
Cooper	O
pairs	O
and	O
create	O
excess	O
quasiparticles	O
.	O
</s>
<s>
The	O
kinetic	O
inductance	O
of	O
the	O
superconducting	O
strip	O
is	O
inversely	O
proportional	O
to	O
the	O
density	O
of	O
Cooper	O
pairs	O
,	O
and	O
thus	O
the	O
kinetic	O
inductance	O
increases	O
upon	O
photon	B-Application
absorption	O
.	O
</s>
<s>
This	O
inductance	O
is	O
combined	O
with	O
a	O
capacitor	O
to	O
form	O
a	O
microwave	O
resonator	O
whose	O
resonant	O
frequency	O
changes	O
with	O
the	O
absorption	O
of	O
photons	B-Application
.	O
</s>
<s>
This	O
resonator-based	O
readout	O
is	O
useful	O
for	O
developing	O
large-format	O
detector	O
arrays	O
,	O
as	O
each	O
KID	O
can	O
be	O
addressed	O
by	O
a	O
single	O
microwave	O
tone	O
and	O
many	O
detectors	O
can	O
be	O
measured	O
using	O
a	O
single	O
broadband	O
microwave	O
channel	O
,	O
a	O
technique	O
known	O
as	O
frequency-division	B-Protocol
multiplexing	I-Protocol
.	O
</s>
<s>
Since	O
their	O
ability	O
to	O
be	O
frequency-division	B-Protocol
multiplexed	I-Protocol
allows	O
KIDs	O
to	O
achieve	O
small	O
detector	O
package	O
sizes	O
,	O
KIDs	O
have	O
also	O
gained	O
popularity	O
in	O
airborne	O
balloon	O
astrophysics	O
as	O
a	O
more	O
compact	O
and	O
less	O
massive	O
alternative	O
to	O
transition	B-Algorithm
edge	I-Algorithm
sensors	I-Algorithm
.	O
</s>
