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1
力学インダクタンスはクーパー対の慣性質量に起因するため、超伝導体に E ＜ hν の5þ )@éĵ/;8uõälķĹě?³DŋŧŬŇoÒĴĦń[ÆãųĆýĔŴĤĲgap)ŜŲŦćŎűŎŮŚŉň;8 )¸ ăāĔĂė~´ýþÿĔýąė ôÿþĂüĒ

エネルギーを持つフォトンが入射しクーパー対を破壊すると力学インダクタンスが変化èĹŎűŠŪŲőūűĴĽńıľěýüöĒ²-^ĥaîĜする。
MKID とはこの力学インダクタンスの変化を読み取る直接検出器である。図 2.2 に<ěÔÖŀë%ĸ"±ĴěŽýúāööďĊēŇÇ¢MKIDおよび等価回路を示す。

ýüüüđĒ [Æãĸ§→ŭŗŖŲŌůŖňűåĵ$åų+víŴ 0.41.5THzĽĴĸÇų È»5”ź1.5THzŴ→j2¯\( <¶O2ĕě<ÕS0.5Ė)ěåí¯\(Ź20um)
58→ 10måĸ>ÇĜêíĸ;¨ķě¬ķŁńĦŇĭń ŇÊĨńĜĚ

5ý ŜŲŦćŎűŎŮŚŉň;81
perconductonatorss by using suisno
ction of phot
ton energy
ns (with pho
h to the deteoming photo
new approac
theirstream of inc
A promisingns, changing
oyidtaaetitcsxe
tor.
rs [16]. The
nto unpairedsuperconducing resonato
ooper pairs isponse of the) breaks up C
frequency relarger than 2ting the highnsities, a⇥ec
respective de.2.3

Figure 1.2: Left: A photon with energy
is absorbed and breaks a Cooper pair,creating quasiparticle excitations on top of the thermal background. Middle: Thevariation in the Cooper pair and quasiparticle densities leads to a change in the kinetic
inductance. Right: Subsequently the resonance frequency of the circuit shifts.
!

N(E)

-30
-10

5-50

5!"0/"0-20ћ"#$!

-100E

quasiparticles

0Cooper pairs

10 ("-"0)/"0.



onith sup erc
photons w

oldCatching cs

0- 10- 20- 30- 10A promising new approach to the detection of photons is by using superconducting resonators [16]. The steady stream of incoming photons (with photon energy
larger than 2 ) breaks up Cooper pairs into unpaired excitations, changing theirrespective densities, a⇥ecting the high frequency response of the superconductor.
5four reflective plates (Sekiguchi, 2014). The shape of reflective plates is spherical surface,
1 K Si Lens
4 K SiLens
curvature radius is 80 mm. The length and diameter of the nested baffle are(dia. = 110 mm)(dia. = and400itsmm)

0

approximately 120 mm and 155 mm, respectively. The carbon based black coating was!"0/"0applied to the back side of the reflective plates. Therefore, the front side and back side ofCatching cold photons with superconducting resonators
57.4

8.3 Designof 850 GHz-bands
Evaluationsof MKID
Array Camera

超伝導カメラ1.2.3

reflective plates act as reflector and absorber, respectively.

ducting re-5

10 ("-"0)/"0A large nested baffle (left of Fig. 7.20) mounted on 4 K consists of conical baffle andブミリ波のフォトンを効率よく吸収するような構造になっている。

ìXķÞħĸôÎr©
ųz>5ŴĸäĹě.ÆÎ>:ĴĹàīĤĪŅĳġĶġĜĴĹÅģĮěŏšťŭĴÓħäĥE7ĭńĩĵĥ¤łŅĳġńĜŏšťŭĴÓħäĹě ¡Ķt]gŇ
ÏĩīĶĥłŕŒśķÄņŅıäĵÈâĪŅĳġńĜë
ŋŧŬĴĸkAÇĴě?ħ
ĸĞÞräğĸĥ{_ĴĦńĜ

レンズアレイ  145（0.4 & 0.85 THz)

ホーンアレイ（1.3 THz) 

18
telescope
A photograph of 608-pixel MKID camera with AR-coated silicon lens array is shown infocus@F/6
Fig. 7.21. The whole size of a module is approximately 60 mm. The center black part

natively, readout can be done in the frequency domain, but this requires couplingeach sensor to a resonator. This complicates large array development.
An example of a pair-breaking detector is a superconducting tunnel junction,
which detects radiation by monitoring the current arising from photo-excitedquasiparticles crossing a very thin insulating oxide barrier [15]. If the barrier isthin enough, quantum mechanics allows electrons to tunnel, i.e. to move throughthe barrier from one electrode to the other. A drawback is that Cooper pairs
can also cross the barrier, this Josephson current needs to be tuned out using amagnetic field. Simultaneously suppressing the Josephson current in an array ofjunctions is di⌅cult as the magnetic field needed may vary among junctions, due
to variations in the barrier area or properties. This makes tunnel junctions lessfavorable to place in large arrays.
So far, the readout of many pixels has proven to be a formidable obstacle forthe development of large arrays as individual pixels require their own amplifiers
and cabling, resulting in complex readout schemes as well as the transfer of heatthrough the cabling. Most importantly however, the sensitivity of large arrays isat present not high enough for space-based background-limited detection.
correspond to the AR-coated silicon lens array. The cooling time from 300 K to 100 mKof optical measurement setup is approximately 60 hours as shown in Fig. 7.22. The
system includes a 608-pixel MKID camera, cryogenic wiring, coaxial cabling, baffles, twodielectric lenses and IR blocking filters. As shown in the black line in Fig. 7.22, 608-pixel

24

Chapter 2. Millimeter/Submillimeter-Wave Kinetic Inductance Detector Ca

MKID camera has been cooled to 100 mK when the camera observed the 300 K blackbody

load. The dilution refrigerator constructed by Taiyo Nippon Sanso Co., which was used
this optical measurements, was well-cooled, easy handling and compact system.

camera@F/1 focus

HDPE window(dia. = 340 mm)

MKID Array

それぞれのホーンは 2F λ ∼ 15.7 mm 程度 1 で並べる
cold baffle
ビームサイズは約 15′′ であり、ここで計画しているホーdB. These parameters were summarized in chapter 5, Fig. 5.1.
度に観測できる。15′′ の分解能があれば、1 kpc 先の分
The optimized parameters of the extension thickness, the gap height and the lens
衛星の 100 GHz 帯のビームサイズは約 10′ 程度であるか
Figure 2.6:
diameter were L/R = 0.34, H/R = 0.604 and D = 2.4λ (λ = 353 µm; the wavelengthof A concept of frequency multiplexing of MKIDs.
的にさらに 40 倍ほど細かく分解することができる。13 C850 GHz), respectively. In this simulation, the detector spacing was equivalent to the lens
レースできる。
diameter. Figure 8.7 shows the simulated beam patterns of integrated
siliconlens arraywith HEMT
technology.

申請者の担当部分
at (Left) 810 GHz, (Middle) 850 GHz, and (Right) 890 GHz. Good-quality beam patterns

申請者は検出器の各構成部品の設計、製作、性能評価
with symmetry mainlobe, low-sidelobe level less than − 15 dB and cross-polarization

1Z¢

2Z¢

3Z¢

Noise 5Z¢Z¢
42.2.5

6Z¢

7Z¢level less than − 20 dB were achieved by optimizing the parameters of lens array. を行なう。本申請書で提案する検出器の構成部品を表 2 に56 ŜŲŦCŎűŎŮŚŉň;8ļĸŮŲś

zÞå

Chapter 1. An eye for the sky,÷ŻøêÑŵİŃUĤłŜŲŦćļĸÔÖĸ;|ųÝýþsçŴĜ

Figure 8.8: A module design of 850-GHz band camera. (Left) Green part showed図
the2: 37 個のホーンが並んだホーンアレイ。図 3: 導波管
silicon substrate, and the bottom space is used for the carbon based absorber. (Right)
伝導回路のThe camera module with the 2977 pixel silicon lens array and the springs for fixing thecamera module and the lens array.

ųżŴQ9¯MÍĹQ9óÀĴ£mÛnĿ.»

まとめた。
The theoretical noise limit of MKIDs is dominated by the random generation of q
真空容器
8.3.2 Camera Mountparticles and the subsequent recombination, generation-recombination noise. The g
真空容器は MKID 部分が ∼100 mK のオーダーまで冷$recombination noiseやす必要があるが、真空容器の設計方法自体はすでに確
limited Noise EquivalentPower (NEP)
is described as follow (S!
Figure
8.8 shows a CAD
drawing of a 850-GHz band camera module. 2977 pixel MKIDs
etal., 2002).
立しているため、それにしたがって丁寧に設計と熱計算
$$are mounted on the camera module with a diameter of approximately
50mm. Thegreen
ることを考え、45 m!鏡の構造体と干渉しないことが挙げ
and gray parts correspond to the silicon substrate and silicon lens array, respectively.
√2∆ Nqp (T )光学素子
NEP(T)=[W/Hz],
gr
Gold-plated copper module with two SMA connectors for readout of the microwave sigητqp (T )ホーンを並べる間隔の関係から、45 m 鏡の焦点距離を
nals was used. As shown in Fig. 8.8, the camera module has hexagonal shape. In this  where∆ is the superconducting
その光学設計を行なう。また、真空窓からの赤外線放射
energy gap, η is conversion efficiency of incident pcase, several modules can be assembled into a larger array which fits the circular focal
バッフルなどを設置する必要がある。従来はenergy into quasi-particles
and typically 〜 0.6 (Kozorezov et al., 2000),1N視野のみ
qp is the qplane (Lee et al., 2008).
視野) の光学系に対してどのように最適化すればよいの
particle number of thermal excitations, τ is quasi-particle recombination lifetime, aFigure 8.9 shows a CAD drawing of a 850-GHz band camera for the 10-m Antarctica
も詳細な検討を行う予定である。
is the bath temperature of the MKIDs. As will be noted from Eq. 2.11, the reduct
ホーンアレイthe quasi-particles density and the extension of the quasi-particle lifetime lead a
最近になって広帯域のコルゲートホーンを作ることがsensitivity of a MKID.
ムのホーンアレイが作られる予定であり、図 2 のような
The quasi-particle
number of thermal excitations (Nqp ) is given by:る可能性がある。申請者はホーンアレイの開発には他の超伝導回路
申請者は主に超伝導回路の設計、製作に注力する。図
Nqp = nqp V,
導波管の先に図 3 のような回路がそれぞれ取り付けられ
where nqp is the densityof quasiparticles and V is the volume of MKID.
In the thする。本申請書で提案する超伝導回路は直線2 偏波を検6ĹÜáĴĠńĜŸx ų-80ŴêŸªêĹZpcmĵRĶġĥŕŊũŨűŜŕŒśĥ¼Ģ;¨ŸêíķÊ¹ĭńĥīěħ
ë%ŸT ŀ ÇųêěÎ>Aq¬ŴĵyÔÖŸİŃÔÖ

5ă÷Đø¦½E

ŜŲŦĻĬ;8ĴĸzÞåĸÊ¹Û}quasiparticle



ћ"#$!



((((N(E)))

2π
ω0 = !
4l (Lg + Lk )Cs

53 1998Zĸ6ěěòÙųMicrowave
KineticInductance
ダブルスロット(2.9)
アンテナ
DetectorŴĵ3ĺŅńÐ P4Ňで表される。ここで、l は共振器の長さ、Lg , C は超伝導配線が持つインダクタンス、キャġńĜĄāüöĉĊēWÿ(³DĸŋŧŬĤパシタンスである。MKID に Egap ＜ hν のエネルギーを持つフォトンが入射しクーパー対łŒŔŲśĭńĥěĀüüöĉĊēĤłýúÿöďĊēMKIDを破壊すると力学インダクタンスが変化することから、共振周波数は入射光子Cĸ?¿ŋŧŬļĵæ ŇÚľńĜčČċĈ2πω0 − ∆ω0 = !
(2.10)
Lg+LkŇôf\Ĵ'ĪįńıľķüúýöČ²ĸ100 um4l (Lg + Lk + ∆Lk )CC ŇaÃĵĭńĥěë%#となり、図 2.3 に示すように低周波側にシフトする。
また、図 2.4 に示すように端では電流が最大、電圧が最小であり、openB)d(Figure 7.21: short
A photographof 608-pixel MKID camera
withAR-coatedsiliconlens
array.端では電nĿÌðĴĠńĜÉĴĹěĀüüöĉĊēùöiosism511 MKIDĵYíň 512 ŢŰśŔŊŢĸ220tr a n s
圧が最大、電流が最小となっている。力学インダクタンスの変化に対する感度、つまりűřŝĄāüöĉĊēùöýÿüüöĉĊēĸŶŞűŜĴ0É±GHzW600³DŋŧŬĜ
MKID の感度は short端で最大となるためshort 端でフォトンをたくさん吸収しクーパー
andapproximately 1 mm-size silicon-carbide-grains
act as scattering substance for thefrequency range
millimeter-waveMKID
to terahertz.
対を破壊したい。そのため図2.5fromに示すように
では short 端にアンテナを付けてサýĂüüü³DĸŋŧŬĵĶńĜ
Cooper pair( Ishii+ 2008, Seta+ 2012)!

54→ 220 GHz@×ÜĸK

55→ @×Üĸ
e

#

←510 ·ÈœŠśZEMAXķŁ
最初に述べたように MKID とはマイクロ波帯で動作する超伝導共振器であり、等価回路ńíŒŤŗśŕŊňōŬŦËから分かるようにキャパシタンスとインダクタンスが並列接続された構造を持つ。また、
"MKID では共振器の長さは読み出しに使用するマイクロ波 (一般には 4 - 8 GHz) の 1/4 波
長になっており、片側 short , もう片側が open になっていることから長さに対応したマイ
Chapter 7. Development of a Wide-Field Camera System for Millimeter-WaveýüöĒåĸÇÁ¹Ĝ³DĹčČċĈĎ
クロ波で共振を起こす。この時、共振周波数
ω0 は
134Observations
ir,a Cooper pa
and breaks
is absorbed
le: Theenergyund. Middor
hoton withermal backg
hinetic: Left: A p
top of the tange in the kFigure 1.2
citations on
leads to a chsiparticle ex
icle densities
truit shifts.
creating qua
and quasipa
riay of the circpnce frequenc
the Coopertransmission
resona(dB)variation inequently theRight: Subs
inductance.

220 GHzĸ@×ÜJĴě} ĸdġ=ĴĿALMAŏŊśĸx¾{ųŴĵ1¬ĴěHJcĹŅĳġńµŇ`ıų5ŷŴĜÉ®ŇġıŐŪťůŲŐūű
ĴĹě1 THzŇÐģńï:ĿÇĥ.»ĴĠńĜs crs electron
ooper pairquasiparticle
chanics allow
ack is that C
quantum me
r. A drawb
ehtout using athin enough,rode to theo be tuned ottcsderom one ele
array ofn current ne
the barrier f
his Josephso
current in ant,nos
hs the barrierns, dueng the Josep
can also crosmong junctio
sly suppressiauoyerav
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eld needed mmagnetic fie
nel junction
e magnetic fi
s makes tun
di⌅cult as thperties. Thi
junctions isr area or pro
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e arrays.
formidable oaplace in largroven to bepsaamplifiers
favorable toany pixels h
ire their own
eadout of ml pixels requaudi
er of heatv
So far, the rrrays as indias the transf
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the developm
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he sensitivity
resulting inly however, t
and cabling,d detection.
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through thegh for spaceot high enouat present ns-59→ şŲŦ Öňűřŝ°Ĺěåě$åě!wåĴ gųF6ŴţřŰŕŊű,ĵěëŋŧŬĹě!wåķŁŃġĮŅĤŇßi
図 2.2: (左)MKID (右)MKIDの等価回路 (Barends, 2009)ŜŲŦć