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Contents:
Topics- What’s New in the World of Superconductivity (February)
Feature Articles : Superconducting Microwave and Terahertz Technology- New Evolution of Superconducting Electronics: From Microwave to Terahertz Photonics-Technical Challenges for Application of Oxide Superconducting Films to High-powered Microwave
Devices- Development of Millimeter- and Submillimeter-Wave Mixers- Remote Sensing Technology by Millimeter- and Submillimeter-wave Band Mixer- Direct Detection and Imaging of Terahertz Waves by Superconducting Tunnel Junction Detector Array- Patent Information
Standardization Activities- Topics in December 2006
- Topics in February 2007

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This work was subsidized by

Japan Keirin Association

through its Promotion funds from KEIRIN RACE.
http://ringring.keirin.go.jp

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What’s New in the World of Superconductivity (February)

Power
American Superconductor Corporation (February 1, 2007)
American Superconductor Corporation (AMSC) has announced its financial results for the third
quarter ending December 31, 2006. Revenues for the third quarter decreased to US $9.5 million, comparedwith $13.5 million for the same period in the previous fiscal year. The net loss was also $9.5 million,
compared with $7.5 million for the same period in the previous fiscal year. These quarterly results were
foreseen and were caused in part by funding delays from the U.S. Department of Energy and a technicaldelay in the 36.5-MW motor being manufactured for the U.S. Navy. AMSC ended the quarter with no debt
and $41.6 million in cash, cash equivalents, and short-term investments. The company reaffirmed its
previous forecast of revenues between $50 - 52 million and a loss of between $29 - 32 million for fiscal
2007. As of December 31, 2006, AMSC had a total backlog of $43.2 million in orders and contracts. Thisbacklog has since increased to more than $65 million as a result of AMSC’s acquisition of Windtec™.
Based on new orders that the company expects to close in the fourth quarter, the total consolidated
year-end backlog is expected to increase to approximately $70 million as of March 31, 2007, $60 million ofwhich should be recognized as revenue in fiscal 2008.
Source:“AMSC Reports Third Quarter Fiscal 2007 Financial Results”
American Superconductor Corporation press release (February 1, 2007)
http://phx.corporate-ir.net/phoenix.zhtml?c=86422&p=irol-newsArticle_Print&ID=956807&highlight
American Superconductor Corporation (February 6, 2007)
American Superconductor Corporation (AMSC) has received an order for a 20-megaVARs Dynamic
VAR (D-VAR) system for the Hallet Wind Farm in Australia. Once completed, the Hallet wind farm will be
one of Australia’s largest wind farms, with a capacity of 94.5 MW (enough to supply zero-emission electricity
to 54,000 Australian homes). The order was placed by Suzlon Energy Australia Pty. Ltd. (SEA). The D-VAR
will be delivered to SEA during the second half of calendar 2007, at which time it will be installed in a utility
substation connecting the wind farm to the national power grid. The wind farm should be operational in early
2008. Chuck Stankiewicz, Senior Vice President of AMSC Power Systems, commented, "This new orderfrom Suzlon demonstrates our growing international presence and our close working relationship with theindustry's leading wind turbine manufacturers. With more than $1 billion in annual revenues and in excess
of 7,500 employees, Suzlon has rapidly built a substantial presence in the wind energy market in the
Asia-Pacific region. We are pleased to be working on this important project and look forward to growing ourbusiness with Suzlon."
Source:“AMSC Receives D-VAR(R) Order from Suzlon Energy for Australian Wind Farm”
American Superconductor Corporation press release (February 6, 2007)
http://phx.corporate-ir.net/phoenix.zhtml?c=86422&p=irol-newsArticle_Print&ID=958988&highlight
American Superconductor Corporation (February 13, 2007)
American Superconductor Corporation (AMSC) announced that Hyundai Heavy Industries Co. Ltd.

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Tel: +81-3-3431-4002, Fax: +81-3-3431-4044(Hyundai) has achieved world record performance levels for its fault current limiters (FCL), which weredeveloped using AMSC's 344S superconductors. Hyundai, headquartered in South Korea, began
development of its FCL in partnership with Yonsei University in late 2004. They have since developed a13.2-kV/630-A FCL with a capacity of 8.3 MVA using superconducting coils fabricated with wire from AMSC.
The device was operated at a voltage of 13.2 kilovolts (kV), which corresponds to a three-phase power
equipment voltage class of 22.9kV – a new world record for fault current limiters. The FCL was tested at the
Korea Electrotechnology Research Institute (KERI) in December 2006, where it achieved an AC withstandvoltage of 143 kV (nearly three times higher than the project’s 50-kV goal). Dr. Bok-Yeol Seok, principle
researcher of the FCL project at Hyundai Heavy Industries, commented, "We see tremendous opportunities
for FCLs in the near term and are pursuing this market aggressively. We will continue our development
efforts and now have our sights set on producing 30 to 60-kV FCLs for distribution systems as well as
154-kV FCLs for transmission voltage levels." The FCL program in South Korea is funded by the Ministry of
Science and Technology through the Development of Advanced Power Systems by Applied
Superconductivity Technologies (DAPAS) program. Hyundai is one of eight companies around the world
who are developing FCLs using AMSC's proprietary 344S superconductors.
Source:“AMSC's 344S Superconductors Utilized by Hyundai Heavy Industries to Successfully Develop
Commercial Grade Fault Current Limiter”
American Superconductor Corporation press release (February 13, 2007)
http://phx.corporate-ir.net/phoenix.zhtml?c=86422&p=irol-newsArticle_Print&ID=962312&highlight
National Institute of Standards and Technology (February 15, 2007)
Researchers at the National Institute of Standards and Technology (NIST) have reported that a small
mechanical strain can cause a large, but reversible, drop in the maximum current that can be carried byhigh-temperature superconductors. Specifically, a 40% reduction in the critical current of three types of
YBCO was observed after the application of a 1% compressive strain. The discovery is the first major
reversible strain effect found in practical high-temperature superconductors. This effect will have importantconsequences to the design of superconducting systems, particularly electric power applications. Whileaccommodations for the effect can be readily made, knowing about it in advance should contribute to thesuccess of many large-scale devices. The research was reported online in Applied Physics Letters(January 31, 2007). The researchers are now examining how magnetic fields affect the strain effect.
Source:“Strain has major effect on high-temp superconductors”
National Institute of Standards and Technology press release (February 15, 2007)
http://www.nist.gov/public_affairs/techbeat/tb2007_0215.htm#htc
SuperPower, Inc. (February 27, 2007)
SuperPower Inc. has received a contract from the U.S. Department of Defense’s Office of Naval
Research for the second phase of a program to develop an HTS generator based on its second-generation
wire. The 18-month contract is worth US $3 million. In partnership with Baldor Electric Company’s
Reliance Electric Company, General Dynamics' Electric Boat division, Oak Ridge National
Laboratory, the Naval Surface Warfare Center Carderock Division, and the Naval ResearchLaboratory, SuperPower will use the contract to complete a conceptual design for a 10.6-MW
HTS generator and conduct a risk assessment for a 36.5-MW class HTS generator.
Source:“SuperPower Receives $3 Million Office of Naval Research Contract For Further Development of a

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High-Temperature Superconducting Generator for Application to the Navy's All Electric Ship Program”
SuperPower, Inc. press release (February 27, 2007)
American Superconductor Corporation (February 28, 2007)
American Superconductor Corporation (AMSC) has received new orders for D-VAR® voltage
regulation systems for wind farms in Northern Ireland and Texas. The wind farm in Northern Ireland will be
the eighth wind farm in the U.K. to utilize AMSC’s D-VAR solution. This number is expected to grow as the
U.K. moves towards its goal of generating 10% of its electricity from renewable sources by 2010.
Meanwhile, Texas accounted for nearly a third of all newly installed wind power capacity in the U.S. in 2006.
These orders bring the installed base and orders for D-VAR and PowerModule ™ solutions to more than
2,900 MW of wind power worldwide – tripling the amount served by AMSC solutions only 12 months ago.
The D-VAR solution alone will now be used in 25 wind farms in five countries worldwide.
Source:“AMSC Continues Sales Growth in Wind Energy Market with Domestic and International D-VAR® Orders”
American Superconductor Corporation press release (February 28, 2007)
http://phx.corporate-ir.net/phoenix.zhtml?c=86422&p=irol-newsArticle_Print&ID=968236&highlight

MagnetNorthwestern University (February 11, 2007)
Researchers at Northwestern University have identified Bi-2212 as a material that might be suitablefor fabricating a 30-Tesla magnet. Such a magnet would be the most powerful superconducting magnet in
the world. Presently available low-temperature superconducting magnets for medical and research MRI
applications are capable of attaining a maximum magnetic field of about 21 T. The Northwestern
researchers demonstrated that Bi-2212, when cooled to below 12 K, could be used to achieve the stablestate necessary for a 30-T magnet. The group’s research was published online in the journal Nature
Physics (February 11).
Source:“Physicists set 'speed limit' for future superconducting magnet”
Northwestern University press release (February 11, 2007)
http://www.northwestern.edu/newscenter/stories/2007/02/halperin.html

Electronics
D-Wave Systems, Inc. (February 13, 2007)
D-Wave Systems, Inc., a privately held Canadian firm, has publicly demonstrated the world’s firstcommercially viable quantum computer. Quantum computing is expected to be applicable to areas whereproblems or requirements exceed the capability of digital computing, such as “NP-complete” problems
where the sheer volume of complex data and variables prevent digital computers from achieving results in areasonable amount of time. Furthermore, quantum technology will enable precise answers to problems thatcan only be answered at present in general terms, thereby broadening the scope of computer applications.
Nevertheless, D-Wave emphasized that the new device is intended to complement conventional computers,

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not replace them. The quantum computer utilizes a new type of analog processor based on quantum
mechanics, rather than conventional physics. D-wave intends to use “scalable” processor architectures thatare based on available processes and technologies. For more information, please visit
www.dwavesys.com.
Source:“World’s First Commercial Quantum Computer Demonstrated”
D-Wave Systems, Inc. press release (February 13, 2007)
http://www.dwavesys.com/index.php?mact=News,cntnt01,detail,0&cntnt01articleid=4&cntnt01origid=15&c
ntnt01returnid=21

Communication
ISCO International Inc. (February 22, 2007)
ISCO International Inc. has announced their financial results for the fourth quarter and fiscal year
2006. Revenues for the fourth quarter and full year grew significantly to US $3.8 million and $15 million,
respectively, compared with $2.5 million and $10 million, respectively, for the same periods in the previous
fiscal year. Net loss for the fourth quarter and full year were $1.3 million and $4.4 million, respectively,
compared with $1.1 million and $3 million, respectively, for the same periods in the previous fiscal year. The
year-end backlog was less than $0.5 million. John Thode, Chief Executive Officer of ISCO, commented,“We were able to achieve these results [a breakeven cash flow during the second half of the year] while
making substantial investments in areas that we believe will drive futures revenue opportunities for thecompany, most notably our fully digital interference mitigation produce, which is due to be completed during
this year. We view this as a company-changing event, as we believe it will enable us to penetrate moremarkets, more deeply, than we can contemplate with today’s platforms.”
Source:“ISCO International Reports Financial Results for the Fourth Quarter and Full Year 2006”
ISCO International Inc. press release (February 22, 2007)
http://www.b2i.us/profiles/investor/ResLibrary.asp?ResLibraryID=18956&f=1&BzID=826&Category=135&N
av=1&LangID=1&s=0

Basic
Carnegie Institution of Washington (February 26, 2007)
Researchers at the Carnegie Institution's Geophysical Laboratory, in collaboration with the Chinese
University of Hong Kong, have discovered that pressure and the substitution of different oxygen isotopes
have similar effects on the electronic properties of high-temperature superconductors. The group’s results
suggest that phonons within the lattice structures of these materials are essential to the phenomenon ofsuperconductivity. Xiao-Jia Chen, lead author of the study explains, “In this study, we found that by
substituting oxygen-16 with its heavier sibling oxygen-18, the transition temperature changes; such a
substitution is known as the isotope effect. The different masses of the isotopes cause a change in lattice
vibrations and hence the binding force that enables pairs of electrons to travel through the material without
resistance. Even more exciting is our discovery that manipulating the compression of the crystalline lattice ofSpring, 2007

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the high-Tc material has a similar effect on the superconducting transition temperature. Our study revealed
that pressure and the isotope effect have equivalent roles on the transition temperature in cuprate
superconductors." The group also determined that phonons could account for both the magnitude of theisotope effect as a function of the doping level and the variations seen among different types of cuprate
superconductors as well as how modifications of the electronic structures among various optimally doped
materials influence the superconducting properties. Collectively, the results represent a unified picture forthe oxygen isotope effect in cuprates at ambient condition and under high pressure. The group’s research
was published in the online edition of the Proceedings of the National Academy of Sciences (February 26 March 2). The Office of Basic Energy Science and the National Nuclear Security Administration of the US
Department of Energy and the Hong Kong Research Grants Council supported this study.
Source:“New insights into high-temperature superconductors”
Carnegie Institution of Washington press release (February 26, 2007)
http://www.carnegieinstitution.org/news_releases/news_2007_0226.html(Akihiko Tsutai, Director, International Affairs Department, ISTEC)(Published in a Japanese version in the February 2007 issue of Superconductivity Web 21)

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Feature Articles: Superconducting Microwave and Terahertz Technology- New Evolution of Superconducting Electronics: From Microwave to
Terahertz Photonics Masayoshi Tonouchi, Professor
Laser Energy Science Research Laboratory
Osaka University
The application of high frequencies is an important issue to superconducting electronics. To date,
the application of SIS junction to radio astronomy has been made and in the United States, ahigh-temperature superconducting microwave filter and other devices have been commercialized, while
China, meanwhile, is targeting the use of high-temperature superconducting microwave filters during the
Beijing Olympic Games. In Japan, the use of the latter in base stations of terrestrial digital broadcasting isbeing studied. By making these filters high power, they can also be used as power transmission antennas.
Recently, there has been a prominent evolution in the terahertz field, in which superconducting electronics
are expected to play a major role. Aside from high frequency applications, superconducting electronics are
expected to have roles in X-ray sensors, superconducting quantum bits and various other fields. The author
is proposing the creation of “superconducting photonics engineering” merging “superconducting electronics”
and “optoelectronics.”

The development ofanalytical equipment
Nanotechnology

Infocomunicatiion

Optical communication
components

Optical routers

New function
analysis
Development of new
function materials

Limiting high-speed
optical sensors

Strong correlation lightfunctions

SFQ optical interfaces
Ultrahigh speed
logic circuits

Optical superconducting
quantum bits

Quantum computers
Next-generation
computers

New novel property
physics

Superconducting photonics
engineering
Laser SQUID
Optical terahertz wave
sensing

VLSI fault analysis
systems

Terahertz analysis andimaging systems
Safety and security

Basic science

Bio and medical

Fig. “Superconducting photonics engineering” - New superconductivity research field

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As illustrated in the diagram, superconducting photonics engineering covers a wide scope, from
X-rays to microwaves, as well as application targets such as optical communication components, opticalrouters, super high-speed logic circuits, quantum computers, new function analysis, imaging equipment and
VLSI fault analysis systems. Superconducting photonics engineering can make a contribution to a variety offields, including establishing a safe and secure society, next-generation infocommunications, and bio
medical and basic science.
Here, optical sensors are the key device, including X-ray sensors which demonstrate outstanding
performance and beginning to come into use. Sensors in the infrared region can also be used in input
interfaces between optical communication signals and super high-speed logic circuits and the developmentof super high speed and low power consumption interfaces for use in SFQ circuits is regarded as vital fornext-generation computers. The rapid evolution of the terahertz field will see various applications emerge forterahertz photon sensors, while devices using SIS and HEB will become indispensable for radio astronomy
and earth environment measurement. Focal plane array sensors will spawn ultrahigh sensitivity terahertz
cameras, paving the way for the development of high value added systems, such as security systems. The
terahertz single photon counter will be a key device in quantum information communication.
Applications such as Laser SQUID that actively use lights can be unfolded and superconducting
quantum bit devices are also attracting attention as key next generation devices, for which new applications
will be found by combining them with lights. It is hoped that a variety of activities will be undertaken tocomprehensively target the creation of new fields.
References
Masayoshi Tonouchi, Research Data 80, 146th Committee Meeting, Japan Society for the Promotion of
Science, p. 2, 2006.
Masayoshi Tonouchi, Applied Physics, 75, 160, 2006.
“Terahertz Technology,” editorial supervision by Masayoshi Tonouchi, Ohmsha, May 2006.

(Published in a Japanese version in the February 2007 issue of Superconductivity Web 21)

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Feature Articles: Superconducting Microwave and Terahertz Technology- Technical Challenges for Application of Oxide Superconducting Films
to High-powered Devices Haruhiko Obara
Energy Technology Research InstituteNational Institute of Advanced Industrial Science and Technologys

R (m Ω)

Passive devices in the microwave band that use oxide superconducting films, such as receiving
band-pass filters, have been successfully introduced to the market for use in cellular phone base stations.
They have also frequently been cited as successful examples of electronics applications for oxide
superconductors, having accomplished commercialization at an early stage. 1) Only a few companies in the
United States, including Superconductor Technologies Inc. (STI), have succeeded in producing them andtheir market size remains modest compared with early expectations. In Japan in particular, superconducting
filter systems are not widely used in the base stations of cellular phones, due to the system that differs fromthat of the United States and to the low cost demand for base stations.
The commercialization of high powered microwave devices, such as signal transmitting filters, is
expected to trigger the penetration of superconducting passive devices. One prominent feature ofsuperconductors themselves is their ability to achieve a high current density as high magnetic field magnets
and as wires for power transmission cables. The diagram plots the relationship between a shielding current
flowing on the film surface of a YBa2Cu3Oy and the surface resistance to 10GHz-band microwaves,measured while varying the
0.5
microwave power. The surface
10.7GHz
resistance varies at a slightly lower
current density, but it remains almost
0.4
constant to a current density thatequivalent to the critical current
density, which suggests the potential
0.3
for superconducting films to power
major microwave applications.
65K
Transmitting filters as
0.2
products will offer advantages, such
55K
as reductions in the leakage of
45K
outside-band
electromagnetic
35K
0.1
waves
without
considerablyincreased costs, as well as the
reduction of transmit amplifier output,0
so research into the application of
4
5
6
7
100
1000
10
10
10
10
high-powered microwave devices is2
actively underway in Europe, theJ (A/cm )max
United States and Japan. In Japan,
Measurement example of maximum current density Jmax of
the Ministry of Internal Affairs andshielding current flowing on the film surface and surface resistanceCommunications has taken up
Rs. The film is a YBCO film, manufactured by THEVA and about
superconducting filter technology in
500nm thick.
its research and development for

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the expansion of radio wave resources and is sponsoring a project aimed at the commercialization oftransmitting filters. 2)
The development of a film, device and system that excel in resistance to power is needed to
produce transmitting filters. However, the device and system development face many research challenges,
including a device design that differs from that for receiving devices 3), and removal of the heat entry fromtransmission lines. There is a tendency to consider producing films that have the excellent power resistancecharacteristic of superconductors relatively easy, thanks to the advances achieved in film manufacturing
technology. However, microwave devices require a film that is sufficiently thick (normally about 500nm or
thicker) compared with the magnetic field penetration depth of superconductors. Films of a relatively large
thickness, as mentioned above, and featuring superconductivity characteristics and surface smoothness,must be manufactured stably, since rough surfaces of superconducting films, cracks and other defects inparticular prominently degrade the microwave characteristics. A low-cost dielectric substrate is also
necessary for inexpensive superconducting devices and numerous research challenges must be
addressed, such as the fabrication of quality superconducting films onto a sapphire substrate.
Regrettably, Japan has lagged behind the United States in terms of the commercialization ofreceiving filters, although it remains fully capable of competing with the latter on a technical level. Supportedby the state through the sponsoring of a national project, the potential for Japan to seize the initiative increating a new market for superconducting passive devices for high-powered microwave application are
high.
References
1) E.g. feature articles in “Superconductivity Web 21,” February 2006.
2) For a project overview, visit http://www.soumu.go.jp/s-news/2005/pdf/051027_1_1.pdf.
3) K. Yamanaka, A. Akasegawa, M. Kai, et al., Physica C - Superconductivity and Its Applications 445, 998(2006).

(Published in a Japanese version in the February 2007 issue of Superconductivity Web 21)

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Feature Articles: Superconducting Microwave and Terahertz Technology- Development of Millimeter- and Submillimeter-Wave Mixers Takashi Noguchi, Associate Professor
Advanced Technology Center
National Astronomical Observatory of Japan
1. Introduction
Superconductor-insulator-superconductor tunnel junction (SIS junction) devices are widely usedas heterodyne mixer devices in high-sensitivity receivers for the observation of extremely feeble cosmic
radiations at the millimeter- and submillimeter-wave bands. Since mid 80s, the National Astronomical
Observatory of Japan has been conducting to develop Nb-based SIS junctions and low-noise millimeterand submillimeter-wave receivers using those SIS junctions. This paper describes the current status of
R&D of the SIS mixers, which is the key component of the high-sensitivity receivers used in theobservation of cosmic radiations.
2. Current Status of Low-Noise Receivers Using SIS Mixers
Due to the existence of the energy gap in Nb (2∆~3 meV), a current rapidly increases at the gap
voltage Vg (= 2∆/e; e is the charge of an electron) in the current-voltage characteristics of a Nb/AlOx/Nb SIS
junction. Using this strong non-linearity at the gap voltage, the SIS mixer can detect electromagnetic waves
with high efficiency. If a leakage current of the SIS junction is very small in the sub-gap region, and the risein current at the gap voltage is very sharp, a noise temperature near the quantum limit, hν/kB, can beachieved in the SIS mixer, where h, kB and ν represent Planck’s constant, Boltzmann constant and a signal
frequency, respectively.

77K noise
inputWith LO input
Without LO input

Receiver noise temperature (K)300K noise
input

Receiver noise temperature (K)IF Output Power (dBm)

DC current-voltage
characteristic

ALMA-specification noise temperaturelevel (Optional frequency)
ALMA-specification noise temperaturelevel (80% of total bandwidth)

Voltage (mV)

Frequency (GHz)

Fig. 1 Performance of a 500-GHz band receiver that uses an SIS mixer.
(a) DC I-V characteristics of a SIS mixer with and without local oscillator (LO) and its IF response as afunction of frequency. (b) Frequency dependence of the receiver noise temperature of SIS mixers. The twostraight lines represent the noise temperature required for the SIS mixers to be used in the Atacama Large
Millimeter/Submillimeter Array.

Figure 1(a) shows the DC I-V characteristics of a 500-GHz band SIS mixer and its IF output as a

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Receiver noise temperature (K)function of voltage when radiations from standard noise sources at room temperature and 77K are applied.
Minimum signal-to-noise ratio of the SIS mixer is obtained at the voltage of the IF peak just below the gap
voltage and the input equivalent noise temperature in this case is called a receiver noise temperature TRX.
Figure 1 (b) plots the frequency dependence of the noise temperature of a typical 500GHz-band receiver. It
is demonstrated that a minimum receiver noise temperature TRX of 60K (at 430GHz), which is only about
three times the quantum-limited noise temperature of hν/kB, can be achieved.
The noise temperatures of the SIS
receivers at the millimeter and submillimeter
wavelengths reported previously are plottedin Fig. 2. It is shown that receivers with very
low noise have been built from 100 GHz to1000 GHz. It is clearly demonstrated that thenoise temperature of radio receivers using
Schottky diodeNb-based SIS mixers are about 3 times themixer
quantum limit (3hν/kB) at frequencies below
700 GHz, but that the noise temperature of
the receiver rapidly increases at frequencies
above 700GHz. This can be attributed to anincrease in losses of the Nb film used for thewirings and tuning (resonance) circuit, due tothe absorption of electromagnetic waves witha frequency above the Nb gap frequency
Frequency (GHz)(about 700 GHz). At the Advanced
Fig.2 Noise temperatures of radio receivers at millimeterTechnology Center of the Nationaland submillimeter-wave frequencies using the SIS mixer
Astronomical Observatory of Japan hasreported to date. Abbreviations in the upper left panel
been currently starting to develop SIS mixers
represent the research organizations. NAOJ: National
employing a Nb-based SIS junction in
Astronomical Observatory of Japan, SRON: Space
combination with a NbTiN thin film with low
Research Organization of the Netherlands, Caltech:absorption loss near 1THz, aiming to build a
California Institute of Technology (USA), NRAO: National
low-noise SIS mixer at around 1 THz.
Radio Astronomy Observatory (USA).
3. Conclusion
It has been past just 20 years since a 40-GHz band receiver using an SIS mixer was installed andused in the 45-m radio telescope at the Nobeyama Observatory of the National Astronomical Observatoryof Japan in 1987. During the past two decades, a lot of great effort has been put into the research of SIS
mixers not only to improve their noise performance but also to extend their application frequency. Now it ispossible to build high-performance SIS mixers and receivers with noise performance approaching aquantum limit at frequencies as high as 1 THz. At present, we are developing a 150-GHz and 450-GHz
band SIS receivers to be installed and used in the Atacama Large Millimeter/Submillimeter Array (ALMA),
the world’s largest interferometer telescope at millimeter and submillimter wavelengths being built in the
Atacama desert at an altitude of about 5000 m in northern Chile as illustrated in Fig. 3. The first SIS
receivers are scheduled to be shipped to Chile at the end of this year or early next year.

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Fig. 3 An artist’s image of the Atacama Large Millimeter/Submillimeter Array(ALMA), which will be completed in construction by the end of 2011.

(Published in a Japanese version in the February 2007 issue of Superconductivity Web 21)

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Feature Articles: Superconducting Microwave and Terahertz Technology- Remote Sensing Technology by Millimeter- and Submillimeter-wave
Band Mixer Yoshihisa Irimajiri
Environmental Information and Sensing Network Group
Applied Electromagnetic Research Center, Research Department 3
National Institute of Information and Communications Technology (NICT)The millimeter- and submillimeter-wave band superconducting receiver system is one of thepowerful tools to observe stratospheric trace gases related to ozone depletion and global warming (HOx,NOx, ClOx, BrOx). Radio spectra radiated by molecules are received by the heterodyne system and thealtitude distribution of these molecules is measured in high sensitivity and high altitude resolution via atechnique to observe the limbs of the atmosphere called the “limb sounding method.”
Our Group developed a balloon-borne superconducting submillimeter-wave limb-emission
sounder (BSMILES) and conducted ballooning tests at the Sanriku Balloon Center of the Institute of Spaceand Astronautical Science (ISAS) of Japan Aerospace Exploration Agency (JAXA) in 2003, 2004 and 2006
respectively. BSMILES consists of an antenna-calibration system, optics system, receiver system,
intermediate frequency system, spectroscopic system, data acquisition and control system, attitudedetection system, power source and balloon engineering system (command and telemetry system andother systems). Fig. 1 shows a block diagram of the system. The gondola measures about 1.35m x 1.35m
x 1.26m and weighs about 600kg in total, consuming about 150W of electricity. The submillimeter-wave
band contains many radio wave spectra radiated by atmospheric molecules, with strong radiation intensities,
which are advantageous to observation. Moreover, observation unaffected by the absorption of water vapor
in the troposphere will be possible by lifting the system into the stratosphere via a balloon.
The antenna system consists of a plane mirror for beam scanning, an offset parabolic antenna
300mm in diameter and a secondary mirror. Calibration data is obtained by changing to a hot load and coldsky (elevation angle 50°) for each scan via a switching mirror for calibration. The receiver contains asubmillimeter-wave (650GHz) band superconducting receiver, cooled to 4K by liquid helium, and asuperconductor-insulator-superco
cold skyyreferencenductor (SIS) mixer. The SIS
beam-scanning mirror(EL 50 o)antenna anddevice is a Nb/AlOx/Nb of thecalibration systems
stepping motor
PCTJ type.1)The best value of thecommand/spectralptelemetry
analysisy
DSB system noise temperature atmosphericsystems
systemsignal(measured in front of the antenna)
dataof the SIS mixer is about 300K in
handling toIF system
groundsystemthe 630GHz band. After being
supportsystemsubreflector
converted into an intermediate
attitudereceiverdetection
frequency (5 to 7GHz) by thesystemsystemswitchingmirrori
mixer, the signal is amplified by amain reflector
powerhigh electron mobility transistor
opticssupply(HEMT) amplifier (cooled to 15K)
hot loadandambient-temperatureamplifier and its spectrum isFig. 1 Block diagram of BSMILES
obtained by an acousto-optic
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Brightness Temperature (K)spectrometer (bandwidth 1GHz, resolution about 1MHz). The data obtained is recorded in a PC card of thepersonal computer installed in the balloon and then recovered at sea. A tri-axial fiber-optical gyroscope,tri-axial accelerometer, and dual-axis geomagnetism sensor to detect the gondola attitude are installed. The
equipment is contained in a pressurized container sealed with nitrogen gas for waterproofing and noise
shielding and powered by a lithium battery designed to provide power for 30 hours.
Fig. 2 shows spectra of O3,
35
37
O3
H Cl
H Cl
60
O3 isotope, H35Cl, H37Cl, HO2 andothers obtained during observationo17
EL=-2.1
OOO (usb)
in 2004. This data was obtained by50
scanning in an altitude direction. The
O 3-v1,v3
integral time of one spectrum is
40
18
(usb)
17
O 3-v1,v3
O OO
about one minute. The observation
OOO (usb)HOo2
succeeded in the short-time-1.030
observation of trace molecules thato+0.1
radiate an extremely weak radio
20owave called HO2. The system noise+1.2
HO2 (usb)level (r.m.s.) was about 70mK.
624.22624.72625.22625.72(lsb)
638.22637.72637.22636.72 (usb)Thesuperconducting
Frequency (GHz)submillimeter-wave
bandreceiver installed on a balloon can
Fig. 2 Radiation radio wave spectra of O3, H35Cl, HO2 and others
simultaneously observe ozone andtrace molecules related to the ozone depletion and represent one of the powerful tools of atmosphericobservation. A superconducting high-sensitivity receiver installed on the balloon enables the observation of
trace molecules, which was previously impossible, in a short time, thereby solving the photochemical
reaction process and greatly contributing to future forecasts of the ozone layer. By installing a hot electronbolometer (HEB) mixer, a significant contribution to the development of a THz-band heterodyne receiver,atmosphere observation (OH radicals and others) and astronomic observation can be made, in the future
as well.
References
1) J. Zmuidzinas, H. G. LeDuc, J. A. Stern and S. R. Cypher, “Two-junction turning circuits for submillimeter
SIS mixers,” IEEE Trans. Microwave Theory Tech., Vol. 42, No. 4, pp. 698-706, Apr. 1994.

(Published in a Japanese version in the February 2007 issue of Superconductivity Web 21)

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Feature Articles: Superconducting Microwave and Terahertz Technology- Direct Detection and Imaging of Terahertz Waves by Superconducting
Tunnel Junction Detector Array Chiko Otani and Seiichiro Ariyoshi
Terahertz Sensing and Imaging Laboratory, Terahertz-wave Research Program, RIKEN
Tohru Taino
Dept. Electrical and Electronic Systems, Faculty of Engineering, Saitama University
Considerable hope is placed on a variety of spectral analysis and imaging applications in theterahertz (THz) band. Most THz imaging is performed by single-pixel detectors and there is considerable
demand for the development of high-performance array detectors to see through materials with the good
special resolution. The authors are developing two types of high-performance THz wave direct detectors
using superconducting tunnel junction (STJ) devices consisting of a 5-layer film of Nb/Al/AlOx/Al/Nb.
The first detector is a band-type detector arraythat uses photon-assisted tunneling process (Fig.1) . One
element consists of an Nb plane antenna and Nb micro
strip line brideged by twelve STJ devices, and operates
below 0.7 THz in frequency which corresponds to 2∆ of Nb(about 3 meV in energy). This detector electricallyconstitutes a high frequency LCR circuit at its central
frequency of 0.65 THz, with more than 10% bandwidth,
10-16 W/√Hz in noise equivalent power (NEP) and morethan 4 x 106 in dynamic range, succeeding in THz imaging
for the first time for STJ direct detectors. 1) (Fig. 2) The
frequency characteristics of a 5-pixel linear array has been
confirmed to coincide each other2), and the test
observations by a 3x3 array with the ASTE telescope in
Fig.1 6 x 6 pixel on a sapphire substrate
Chile have commenced. 3)
The second sensor uses highfrequency phonons generated on thedetector’s single crystal substrate which
operates as an absorber of THz waves.
When THz photons are absorbed,
high-frequency phonons are generated
in the substrate and reach the STJ
device. When the phonons’ energy is
above 2∆, then they break Cooper pairs
and produce extra quasiparticles in theNb superconductor electrode. Kurakado
Fig.2 Example of THz image (Needle in powder milk)
et al., developed a technique to utilize
the substrate phonons for detecting X-rays and high-energy particles. However, this is the first verification
for detecting low energy photons in the THz band. A flat spectral response in at least 1 to 2THz has been
confirmed, featuring the use of a frequency-tunable THz source. The detectors are expected to play a majorrole as broadband ones suitable for the use of specific absorption spectra of many materials in the THz
region. 4)
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References
1) S. Ariyoshi et al., Appl. Phys. Lett., 88, 203503 (2006).
2) S. Ariyoshi et al., Jpn. J. Appl. Phys., 43, 5637 (2006).
3) H. Matsuo et al., proc. SPIE, 6275, 627504 (2006).
4) C. Otani et al., IEEE Trans. Appl. Supercond., 15, 591 (2005).

(Published in a Japanese version in the February 2007 issue of Superconductivity Web 21)

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Patent Information
Introduction of Published Unexamined Patents in the 3rd Quarter of Fiscal 2006
The following are ISTEC’s patents published from October through December, 2006. For more
information, access the homepange of the Patent Office of Japan and visit the Industrial Property Digital
Library (IPDL).
1) Publication No. 2006-268928 “Superconducting Sense Circuit Driven by DC Power”
This invention relates to a sense circuit driven by a DC power supply in superconducting random
access memories (RAMs). In a earlier DC driven sense circuit, it was proposed that the memory data isdecided to be “1”, if a sense signal falls within a predetermined period from the front edge of the sense
signal, and to be “0” if the sense signal does not fall. This conventional example requires a complex timing
sequence and the operation margin of the bias current is small, thus inappropriate for expansions of thememory capacity. The sense circuit of the present patent is characterized by connecting a novel
sense-line information detection block (SIDB) to the RS flip-flop circuit (RS-FF) of SFQ circuit configuration,in where the SIDB is implemented by connecting a sense-line cascading plural read-gates, a bias-resistor
connected to DC power supply terminal, a load-resistor and an inductor. This circuit configuration enables
these read-gates to change to the voltage state when a cell of read data “1” is selected, transmitting single
flux quantum (SFQ) pulses to the RS-FF as signal data of memory data “1.” When a cell of memory data“0” is selected, the read-gate does not change to the voltage state and no SFQ pulse is generated. This
invention achieves generating an SFQ pulse output with a large bias current margin without a complex
timing sequence even in the case of DC power supply.
2) Publication No. 2006-269347 “Manufacturing Method and Manufacturing Equipment for
Tape-shape Oxide Superconducting Wire”
This invention relates to a heat treatment furnace in which a superconducting long wire ismanufactured by arranging a tape-shape wire coated with a superconductor precursor between a pair ofreels and by reacting the superconductor precursor with a reactive gas while feeding it through a reaction
tube. This invention is characterized by vertically feeding the reactive gas on the tape surface to reactwith the superconductor precursor, following which the gas is exhausted through gas outlet holes arranged
in direction of both sides of the tape. The appropriate number of the gas inlet holes and gas outlet holes
are respectively selected in accordance with the width of the tape, and reaction areas, consisting of gas inlet
and outlet holes, can also be arranged along the tape direction of travel. The conventional systems
facilitate the horizontal gas flow onto the surface of a tape by providing gas inlet holes in positions horizontal
to the tape surfaces, but this generates a difference in the reaction speed of the precursor at the ends ofboth sides of tape as the tape width increases, and finally the uniform superconductive characteristics in thewidth direction cannot be obtained. This invention solves above mentioned problem and can be used forwide tape-shape wire, which makes the wire manufacturing speed increase.
3) Publication No. 2006-270282 “DC Power Driven Superconducting Loop Driver Circuit andDriving Method”
This invention relates to a driver circuit for cell-selection signals of superconducting random
access memories (RAMs), in which single flux quantum (SFQ) devices are adopted. Normally, memory
cell array are two-dimensional matrix array and specified memory cell is selected by supplying selection
signals to a row and a column of the matrix. Selection signals are implemented by amplifying level logic

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signals (square wave signals), for supplying simultaneously to all memory cells belonging to the selectedrow or column. This invention is characterized by the use of a driver-gate consisting of an amplifier-gate(AMP) that generates SFQ pulse train in response to the input of a SFQ pulse, a buffer-gate that prevents
the SFQ pulse train from propagating to the input direction and a magnetically coupled superconducting
quantum interference device gate (SQUID) that is temporarily switched to a voltage state for a period of the
SFQ pulse train, and characterized also by the use of a reset gate of equivalent configuration to that of thedriver-gate. After an input of a SFQ pulse, this driver circuit can generate a desired level signal to asuperconducting strip line with plural memory cells as a load, and can be powered by a DC power supply.
4) Publication No. 2006-278384 “Superconducting Random Access Memory and Manufacturing
Method Thereof”
This invention relates to the structure of memory cell in superconducting random access memory
and the manufacturing method thereof. The structure of memory cell based on this invention is of amultilayer structure including superconducting ground plane layers (GP layers) and characterized bystacking a superconducting loop with Nb-based Josephson junctions and a resistance layer on theuppermost superconducting GP layer.
The other resistance layer, inductance layer and asuperconductive passive transmission line layer that is suitable to high-rate signal transmission are
individually inserted between the superconducting GP layers under the uppermost GP layer. This
invention does not need the ground plane layer on the inductance layer constituting the superconducting
loop and can reduce the size of memory cell. Plural GP layers also effectively shield magnetic fields
generated from the DC power line. Because this invention permits to use a high temperature process,such as plasma CVD, for process before forming Josephson junctions, it becomes practical to use a highpermittivity material for insulation layers.
5) Publication No. 2006-310259 “RE123-based Oxide Superconductor and Manufacturing Method
Thereof”
This invention relates to RE123-based superconducting wires manufactured by a new method.
This RE123 oxide superconductor is characterized by being constructed with a REBa2Cu3O7-δ oxide
superconductive layer and a supporting member that support the superconductive layer which is formed
from a mixed raw material including at least RE2BaO4 and Ba-Cu-O raw material powders. In thisinvention, the heating of mixed raw materials in a low oxygen atmosphere will initially change the Ba-Cu-O
material into a liquid phase (liquid phase component). By further increasing the temperature, the liquid
phase component reacts with the RE2BaO4 raw material (solid phase component with a high melting pointtemperature) and the RE123 phase with crystalline orientation is grown in the new solid - liquid reaction.
This growing temperature of RE123 phase is significantly lower than that for the RE123 phase generationby the conventional melt-solidification using the RE123 raw material.
(Katsuo Nakazato, Director, Research and Development Promotion Division, SRL/ISTEC)(Published in a Japanese version in the February 2007 issue of Superconductivity Web 21)

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Standardization Activities
Topics in December 2006
- 3rd Superconductivity Standardization Panel Discussion With support provided by the New Energy and Industrial Technological Development
Organization, the International Superconductivity Technology Center (ISTEC) sponsored the third panel
discussion on superconductivity standardization at the Nagoya International Conference Hall on October 31,
2006. A total of 32 representatives from five countries (Korea, EU, USA, China and Japan) participated in
the panel discussion. The discussions focused on technological development and future prospects related
to superconducting power equipment and apparatus and were successfully adjourned.
Presided by Prof. Kozo Osamura of the Research Institute for Applied Sciences, the following
eight panelists supplied related information to the panel discussions.
1) Kozo Osamura, Research Institute for Applied Sciences
Current status of superconductivity standardization activities
2) Osamu Horigami, ISTEC/SRL
Market trends of superconducting power equipment and apparatus
3) Yasuzo Tanaka, Director, Standardization Department, ISTEC
Standards denotation matters for commercialized superconducting wires
4) Norikiyo Koizumi, JAEA
Current status of tests on wires for ITER
5) S. S. Oh, KERI
Current status of tests on wires for superconducting power equipment and apparatus in Korea
6) P. X. Zhang, Northwest Non-Ferrous Metal Research Institute
Current status of tests on wires for superconducting power equipment and apparatus in China
7) A. P. Malozemoff, AMSC
Development and test methods for next-generation high temperature superconducting wires
8) H.-W. Neumueller, Siemens AG
Current status of tests on wires for superconducting rotating machines at Siemens AG
Based on the information supplied by the panelists, the following discussions took place:1) Current status of superconductivity standardization activities
It was agreed that superconductivity standardization activities had been continuously undertaken
since 1989, with a focus on IEC/TC90 and with Japan acting as the secretariat, that one terminology
standard and 13 testing standards, or a total of 14 standards, had already been established as international
standards, and that at present, the enhancement of testing standards, maintenance of existing standards,
deployment to product standards and formation of an international consensus through panel discussions
were all being carried out.
2) Marketability of superconducting power equipment and apparatus
Low temperature superconductors and SMES and other equipment and apparatus employing
low temperature superconductors were already on sale on the market. However, full-scale market entry
would follow the market debut of superconducting power equipment and apparatus using high temperature
superconductors.

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A comment was made that the market entry of power cables, rotating machines and others would
come earlier than market forecasts, which stated that the full scale market introduction of superconducting
power equipment and apparatus using high temperature superconductors would come after 2010.
3) Layers of standardization
Layers of superconductivity standardization were explained using SMES systems as an example.
As layers move up from materials to wires, conductors, devices and equipment and systems, specification
requirements became special and discrete so that selection as standardization objects would become moredifficult as the layers move up.
It was agreed that it would be useful to continuously study superconducting wires that werecommonly used in a wide range of superconducting power equipment and apparatus as a layer for
standardization.
4) Standardization related to the ITER Project
The ITER Project would soon procure a large amount of superconducting wires internationallyand purchasing specifications, including a method for tests of characteristics, were being studied.
Organizations capable of conducting characterization tests of cable-in-conduit conductors (CICCs) werelimited globally and local standards had to be used.
On the other hand, Nb3Sn superconducting strands that used CICCs were commonly used and atest method based on IEC 61788-2Ed.2 was basically scheduled for use. However, a one-mandrel method
using a titanium alloy tube could be used in critical current tests in a distortionless state. The development ofa test method on the periodic bending strain effect over the lengthwise direction of superconducting strands
themselves, anticipating CICCs, was agreed as an urgent requirement.
5) Test method of high temperature superconducting wires
Bi wires, Y wires, tape wires, round wires, twisted wires, reinforcement wires and various otherwire varieties were being developed as high temperature superconducting wires. Applied research anddevelopment into superconducting cables, transformers, motors, fault current limiters and other apparatus
was conducted simultaneously.
It was therefore agreed that test methods for high temperature superconducting wires depend
significantly on the constructions of wires and conductors, manufacturing process and application fields,
making them diverse and varied. It was also agreed that standardization was indispensable in future forhigh temperature superconducting wires to be accepted as industrial materials, but that, for the moment,
reference test methods should be written and shared among the parties concerned. It was also pointed outthat they should be handled as quality management matters as they would become industrial products.
The following summary was made as a result of the third panel discussions on technologicaldevelopment and the future prospects of superconducting power equipment and apparatus.
1) The understanding on the current status of superconductivity standardization and on the usefulness andnecessity for international standardization was deepened through the interchange of technical information
on superconducting power equipment and apparatus.
2) It was agreed that the technological development of low and high temperature superconducting wires
should steadily be undertaken to meet diverse needs. Under these circumstances, it was agreed as soundto select parts and materials that were closer to the market and those that were commonly used in manysuperconducting power equipment and apparatus as standardization objects to promote standardization forthe moment.
3) Even though the results of the third panel discussions could not be fully discussed yet, the discussions
were useful in deepening understanding of the necessity to promote international standardization and ingaining more knowledge of superconductivity standardization as was the case with the previous two panel

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discussions. It was agreed that meetings of this nature would become more important in the future also.

A scene during panel discussions(Yasuzo Tanaka, Director, Standardization Department, ISTEC)(Published in a Japanese version in the February 2007 issue of Superconductivity Web 21)

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Standardization Activities
Topics in February 2007
- IEC/TC90 (Superconductivity) establishes new WG12 (Current Leads) IEC/TC90 (Superconductivity) conducted international voting between September and December
2006 on new work item proposals (NWIPs). Consequently, the establishment of a new working group(WG12) was approved. It was decided to start standardization on the characterization test methods ofcurrent leads used in superconducting equipment and apparatus, while the voting also approved theappointment of Prof. Toshiyuki Mito, National Institute for Fusion Science, National Institutes of Natural
Sciences, as a convener.
IEC/TC90/WG12 is tasked to internationally standardize terminology, test methods and otheritems related to current leads for the supply of power to superconducting magnets, superconducting
magnetic energy storage (SMES) systems, superconducting power cables, superconducting transformers,
superconducting fault current limiters, superconducting rotating machines and other superconducting
equipment and apparatus.
Current leads as objects of standardization are made of a normal conductor, such as copper,
and/or a superconductor such as an oxide superconductor.
Unlike standardization of test methods for single basic characteristics in conventional
standardization, the collective standardization of characterization test methods is anticipated ascharacterization test methods for current leads, such as the mechanical characteristics (stress and strain
effect tests) products should possess, thermal characteristics (thermal load test), electrical characteristics(rated energizing test, contact resistance test, voltage drop test, withstand voltage test), hydrauliccharacteristics (rated gas pressure drop test, sealing test), safety factor characteristics (gas flow rate test,
quenching test) and other characteristics.
WG12 will be organized by experts recommended by five countries, the United States, Italy,
Germany, Poland and Japan, and will work under the convener, Prof. Toshiyuki Mito. As experts, Mr.
Masayuki Konno (Japan), Dr. Huub Weijers (USA), Dr. Ballarino Amalia (Italy), Dr. Reinhard Heller(Germany) and Dr. Jacek Sosonowski (Poland) have already been recommended.
The work agenda and target schedules for WG12 are generally as follows:
1) Organize WG12 organization
Spring 2007
2) Prepare working draft (WD)
Summer 2007
3) Propose working draft (WD)
Autumn 2007
4) Propose committee draft (CD)January 2008
5) Propose voting committee draft (CDV)-20096) Propose final draft international standard (FDIS)-2010
7) Issue international standard (IS)
December 2010
(Yasuzo Tanaka, Director, Standardization Department, ISTEC)(Published in a Japanese version in the February 2007 issue of Superconductivity Web 21)
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