Experimental study of Quantum Fluids Using a Rotational Cryostat

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The present research project aimed to construct a rotatable cryostat for the study of quantum liquids at a few tens of milli Kelvin to kelvin temperatures and plann and perform fundamental experiments using this apparatus. This type of rotating cryostat is built for the first time in Japan and in order to make the project meaningfull the subject to study and the main features of the apparatus had been decided at the begining of the project. Namely the study of superfluidity in He films formed in the well controlled porous glasses has been selected as the main subject. The rotational speed was designed to be controlled from the very low speed of 10-4 rad/sec which is required for the production of a macroscopic circulation corresponding to formation of a single quantum circulation, to rather high speed which is neccesarry to produce as many 'free' quantized vortices as possible.The apparatus is built in the basement room 002 of the A-building of ISSP,a special pit is prepared with a RF … More shield for this apparatus and the rotating structure with high tech air bearing and turning system is built. A diolution cryostat with Joule Thomson precooling stage is home made specially for rotation and tested, in addition another cryostat for stationary test purposes is built and used for preparatory experiment.Although the project demands quite a lot of technical and theoretical preparations without much manpower nor funding, we have achieved the highest smooth rotation speed of 6.2 rad/sec while continuous operation of the cryostat below 100 mK.Currently a precice experiment of tortional oscillator is being prepared under rotation. Which has been performed to study the nature of the superfluidity in thin He films formed in well controlled porous glasses in a steady cryostat where thermal conductivity measurements yealding consistent result with former tortional oscillator experiment.A theoretical study of the nature of superfluidity and phase coherency in He films in porous materials has been being put forth and an interesting feature of pi phase shift across a two dimensional porous weak junction is studied.An experimental study of thin porous glass film production enabled the realistic consideration of the micro bridge out of porous glass with the possible pi phase shift. Less