2007 Volume 76 Issue 1 Pages 39-43
Superconductor-Insulator-Superconductor (SIS) junctions based on Nb technology are being studied at National Astronomical Observatory of Japan, and high-quality SIS junctions with an area as small as 1μm2 and a current density as high as 10kA/cm2 have been developed. It has been successfully demonstrated that the noise temperature of receivers employing these SIS junctions is only 3 times as large as the photon noise temperature, hν/kB. On the basis of the SIS mixer technology we have accumulated, we are now aiming to develop very low noise SIS mixers and receivers at 1THz band, which will be employed in Atacama Large Millimeter/Submillimeter Array (ALMA), the world’s largest interferometer telescope at millimeter and submillimeter wavelengths, which will be completed in 2011.
