Development of Superconducting Detectors for Measurements of Cosmic Microwave Background.

Mr. MIMA, Satoru (Okayama University)

Co-Authors: ISHINO, Hirokazu (Okayama University)KIMURA, Nobuhiro (High Energy Accelerator Research Organization (KEK))KAWAI, Masanori (High Energy Accelerator Research Organization (KEK))NOGUCHI, Takashi (National Astronomical Observatory of Japan)WATANABE, Hiroki (The Graduate University for Advanced Studies)HATTORI, Kaori (Okayama University)KIBAYASHI, Atsuko (Okayama University)HAZUMI, Masashi (High Energy Accelerator Research Organization (KEK))YOSHIDA, Mitsuhiro (High Energy Accelerator Research Organization (KEK))SATO, Nobuaki (High Energy Accelerator Research Organization (KEK))TAJIMA, Osamu (High Energy Accelerator Research Organization (KEK))OKAMURA, Takahiro (High Energy Accelerator Research Organization (KEK))TOMARU, Takayuki (High Energy Accelerator Research Organization (KEK))

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ContentsMotivation: LiteBIRDSTJ (Superconducting Tunnel Junction)

◦About STJ◦Antenna coupled STJ detectors

Parallel-connected Twin Junction Microstrip Junction

MKID (Microwave Kinetic Inductance Detector)

Summary

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LiteBIRDLite (light) Satellite for the studies of B-mode polarization andInflation from cosmic background Radiation DetectionPurpose and concept

◦ B-mode polarization detection

◦ Whole sky scan◦ Small & compact design◦ Orbit：L2 or LEO

Detector requirements◦ 2,000 Detectors◦ Frequency 50-250GHz◦ Noise Equivalent Power

~10-18W/√Hz09/Jun/2011 TIPP11 3

Weight : 391kgelectricity : 480W

LiteBIRD

LiteBIRD Collaboration ISAS/JAXA: TAKEI Yoh, FUKE Hideyuki, MATSUHARA Hideo, MITSUDA Kazuhisa, YAMASAKI

Noriko, YOSHIDA Tetsuya ARD/JAXA: SATO Yoichi, SHINOZAKI Keisuke, SUGITA Hiroyuki Okayama Universiry: ISHINO Hirokazu, KIBAYASHI Atsuko, HATTORI Kaori, MISAWA Naonori,

MIMA Satoru UC Berkeley: Adnan Ghribi, William Holzapfel, Bradley Johnson, Adrian Lee, Paul Richards,

Aritoki Suzuki, Huan Tran LBNL: Julian Borrill Kinki University: OHTA Izumi ACCL/KEK: YOSHIDA Mitsuhiro IPNS/KEK: ISHIDOSHIRO Koji, KATAYAMA Nobuhiko, SATO Nobuaki, SUMISAWA Kazutaka,

TAJIMA Osamu, NAGAI Makoto, NAGATA Ryo, NISHINO Haruki , HAZUMI Masashi , HASEGAWA Masaya, HIGUCHI Takeo, MATSUMURA Tomotake

CSC/KEK: KIMURA Nobuhiro, SUZUKI Toshikazu, TOMARU Takayuki SOKENDAI: YAGINUMA Eri UT Austin: Eiichiro Komatsu ATC/NAOJ: UZAWA Yoshinori, SEKIMOTO Yutaro, NOGUCHI Takashi Tohoku University: CHINONE Yuji, HATTORI Makoto Tsukuba University: TAKADA Suguru RIKEN: OTANI Chiko Yokohama National University: TAKAGI Yuta, NAKAMURA Shogo, MURAYAMA Satoshi

Superconducting detectorsAntenna coupled STJ

◦fast response can reduce the dead time caused by the cosmic ray attack

◦wide frequency range achievable for 50-250GHz using either photon assisted

tunneling or Cooper pair breaking with a pure Al STJMKID

◦frequency domain readout thousand detectors can be readout with a single line

◦easy to fabricate◦no bias

TES ◦UC Barkley

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• The STJ has a structure of SIS with the insulator thickness of about 1nm.

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Quasiparticle(electron)Superconductor

SuperconductorInsulator

Cooper Pair

STJSuperconducting Tunnel Junction

S SI S SIDirect Cooper pair breaking Photon assisted TunnelingA photon having energy greater than 2D can break a Cooper pair and generate two quasiparticles, which penetrate the insulator layer by the tunnel effect and are detected as an electric current. A photon having energy less than 2D can also be detected using photon assisted tunneling effect. The valence electron can directly penetrate the insulator and go up to the conducting band with the assist of the photon energy.

Egap=2D

Antenna coupled STJ: Parallel-connected twin junctionPCTJ (Parallel-Connected

Twin Junction）◦ The twin parallel STJs

and the inductance form a resonant circuit.

◦ The circuit accumulates the millimeter wave power that generates the quasiparticles.

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Log-Periodic antenna ( Nb )

wire

STJTransmission line

Log-Periodic antenna

STJ

PCTJ

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8

7μmφSTJ

screen with a pattern

hornpolyethylene lens

the screen pattern

an obtained image

STJ output current

millimeter waveinput

STJ bias

optics

0.3K refrigerator

Fabrication and test for the PCTJ detector

illuminating 80GHz

signature of the photonassisted tunneling

Problems on the PCTJ detectorWe have successfully detected 80GHz

millimeter wave with the photon assisted tunneling effect using the PCTJ detector.

However, there are some difficulties on fabricating the PCTJ detector.◦ The impedance matching between the

antenna and the PCTJ is not easy. We need a fine tuning control for the

fabrication on the insulator thickness and character. related with the Josephson current control

It is not easy to increase the bandwidth. the current design up to ~10% LiteBIRD requires 30% bandwidth, however. 2011/03/28 2011年日本物理学会年次大会 9

Microstrip STJ

2011/03/282011年日本物理学会年次大会 10

refle

ctiv

ity

The microstrip STJ has been proposed by Prof. T. Noguchi (NAO).◦ The condition to match the impedances between the

antenna and the STJ is easier for the microstrip STJ than the PCTJ.

◦ In addition, we have found the microstrip STJ can have wider bandwidth than the PCTJ.

refle

ctiv

ity

frequency: 150GHzbandwidth: 30%strip width :2um

antenna coupled Microstrip STJ

antenna coupled PCTJ

simulation resultsfrequency frequency

Antenna-coupled Microstrip STJDesign

◦ The microstrip STJ has a width of 2mm and a length of l/4 at the resonant frequency.

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antenna（ Nb)

readoutline

Al-ＳＴＪNb transmissionline

Fabrication of antenna coupled Microstrip STJ

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SEM images

Microstrip STJ design

100GHz60GHz

150GHz

Frequency[GHz]

Length[um]

60 ~60100 ~40150 ~20

We have successfully fabricated a pure Al microstrip STJ.

Three different detectors are fabricated for central frequencies of 60, 100 and 150GHz.

First look at the microstrip pure Al STJ performance

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The IV curve seems to be good : the gap energy is measured to be 0.34mV,consistent with the pure Al SIS behavior. But we found the normal resistance is higher than expected by an order. We need more tuning on the fabrication.

0.35K

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Typical Absorption CPW-MKIDs

Microwave feed line

MicrowaveResonator

Frequency shiftP. K. Day et al., Nature 425 (2003) 817.

Absorption(typical) and Transmission MKIDsZ0 Z0

Z0

Z0 Z0

Z0

Z0 Z0

/ 2l/ 4l

2Δf = 0.04MHz=> Q=150,000 Q = 90,000

This leads to enable feedback readout

CPW Al-MKIDs

96GHzIrradiation

=> Improving quality of process : EV, Wet etching, Target purity etc…

Microstrip Nb-MKIDsNb

Si 基板SiO2

Microstrip

CPW

CPW Feed-line

MicrostripResonator

=> Adjusting coupling etc.

•CPW resonator•Aluminum : Tc = 1.1K

f > 88 GHz

Multichroic Detector Array

Design for Multichroic MKIDs

↑4 Polarization×4 Frequency×5 Antenna = 80 ch

Microwave

Readout

Sinuous Antenna Transmission MKIDs

MicrostripNb-MKIDs

Nb

Si substrate

Al2O3

Al

From antenna

・ Diffusion length　 100mm >> Penetration depth・ No diffusion from Al to Nb

SiO2

Based on Transmission Microstrip Nb-MKIDs

Final target :- Multichroic - 2000 ch

SummaryLiteBIRD requires 2,000

superconducting detectorsWe are developing STJ and MKID:

◦PCTJ STJ has detected 80GHz successfully.

◦Microstrip STJ has been newly developed.

◦An antenna coupled MKID has been proposed for the multichroic readout.

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backup slides

Nb

Si substrate

Al2O3

AlSiO2

ＳＴＪ＋ＭＫＩＤｓ

MicrostripNb-MKIDs

Al-STJ== Merit ==・ design is easy (can use current design)・ keep up the Q factor・we can inject electromagnetic wave arbitarily place== Problem ==・ increasing layer

Diffusion type MKIDs readout

2010/12/27 202010年ＫＥＫ年末発表会

From Antenna

・ Diffusion length　 100mm >> Penetration depth・ No diffusion from Al to Nb