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NICT REPORT 21High-frequency terahertz funda-mental technologiesWe achieved a 300-GHz silicon-CMOS receiver integrated circuit and combined it with a transmitter circuit implemented in FY2016. In this way, we achieved 300-GHz operation for both transmission and recep-tion on a silicon integrated circuit. This achievement won a best-paper award for the second time at the IEEE International Symposium on Radio-Frequency Integra-tion Technology (RFIT, August 2017) fol-lowing an award received in FY2015.BioICT fundamental technologiesWe succeeded in producing new molecu-lar devices having promising functions by combining biological molecular modules ex-isting in nature. In this way, we have obtained a foothold toward achieving biomimetic de-vices having some of the superior features of living things. This achievement appeared in the Current Opinion in Biotechnology journal highlighted on its cover page. Quantum cryptography and phys-ical-layer security technologyTaking photon-signal discrimination tech-nology developed as a quantum technology for free-space transmission, we applied it to a quantum-communication receiver for satel-lite/ground-station free-space optical com-munications using a Small Optical TrAnspon-der (SOTA) mounted on a 50-kg-class microsatellite (SOCRATES) and performed a basic quantum-communication experi-ment. The Space Communications Labora-tory of the Wireless Networks Research Cen-ter at NICT developed this SOTA terminal. In this experiment, we succeeded in receiving very weak signals with an average of 0.14 photons/pulse from this microsatellite at a ground station and performed time synchro-nization, polarization axis alignment, and photon-stream bit-pattern decoding against these signals (Fig.3). This was the world’s first experimental demonstration of quantum communication using a microsatellite.Quantum node technologyIn the field of quantum metrology, we developed a new indium-ion cooling method (joint cooling) and improved the accuracy of indium-ion optical frequency standards by 1/10 compared with the cur-rent worldwide maximum value in collabo-ration with the Space-Time Standards Laboratory of the Applied Electromagnetic Research Institute at NICT.Development of a vertical Ga2O3 transistorWe fabricated a prototype version of a vertical depletion mode (D-mode) Ga2O3 metal-oxide-semiconductor field-effect tran-sistor (MOSFET) and evaluated device char-acteristics. Figure 4 shows a cross section-al diagram and an optical micrograph of a vertical D-mode Ga2O3 MOSFET fabricat-ed in FY2017. Figure 5 shows DC current versus voltage output characteristics and transfer characteristics of this device. With this prototype, we achieved the world’s first operation demonstration of a genuine vertical Ga2O3 transistor. DUV optical device technologyWe have developed a new method to de-termine the internal quantum efficiency and current injection efficiency of deep ultraviolet (DUV) light-emitting diodes (LEDs) during current injection. As a result, we have demon-strated, for the first time, an extremely high value of 77% for internal quantum efficiency in a DUV-LED during current injection (Fig.6, left). This result was published in Optics Ex-press as a highlighted paper representing an outstanding achievement of excellent scien-tific quality in this field. We also greatly im-proved light-extraction characteristics and droop characteristics using DUV-LEDs incor-porating newly developed aluminum-nitride (AlN) nanophotonic/nanofin structures (Fig.6, right), and successfully demonstrated the world’s highest continuous-wave output power in excess of 200 mW in a single-chip DUV-LED at a peak emission wavelength of 265 nm. Fig.2 : Upper: Device structure and micrograph of magnetic Josephson junction Lower: Temperature dependence of Josephson critical current and observation of π stateFig.3 : Upper left: NICT optical ground station (OGS) and microsatellite (SOCRATES) orbit (red line)Upper right: Photo of satellite, OGS, and SOTABottom: Transmitted random-sequence signal and received signal at OGSFig.6 : Internal quantum efciencies (left) and 3D far-eld radiation patterns (right) of DUV-LEDsFig.4 : Cross sectional diagram (left) and optical micrograph (right) of vertical D-mode Ga2O3 MOS-FETFig.5 : DC current versus voltage output charac-teristics (left) and transfer characteristics (right) of vertical D-mode Ga2O3 MOSFET