Join project of Study on Polarized Atomic Hydrogen

极化氢原子由于其大量子性，即使在绝对零度下也是气态的，这种最简单、最量子的气体探索了量子系统的许多有趣的特性。如果具有足够高密度的极化氢原子能在低温下被冷却，则在这种气体中会发生玻色-爱因斯坦凝聚（BEC）。然而，人们发现在大体积高密度气体中不能达到BEC，他们正在寻找磁俘获的低密度气体中的BEC。京都大学和库尔恰托夫研究所一直致力于研究液氦表面吸附的极化氢原子。这些氢原子形成了几乎理想的二维玻色气体，并可能成为二维超流体（Kosteritz-Bosseless Transition）。两个小组之间的合作集中在寻找K-T转变。通过合作，京都等人研究了二维氢吸附在超流He上的冷却机制，发现氢吸附在^3He-^4He超流膜上的冷却可达几十mK。库尔恰托夫等人研究了强磁场下氢吸附在He膜上的冷却机制，发现氢吸附在He膜上的冷却与K-目前正在京都进行京都氢装置的合作实验，使用库尔恰托夫的毫米-ESR装置。我们在京都观测到了127 GHz的氢原子ESR信号。明年，我们将继续合作，尝试探测二维氢信号和寻找该系统的K-T跃迁。

Polarized atomic hydrogen is in a gas phase even at absolute zero degree due to large quantum nature, and this simple and most quantum gas has explored many interesting features of quantum system. The Bose-Einstein condensation (BEC) has been predicted in this gas if polarized atomic hydrogen with a sufficient high density can be cooled at low temperatures. However, it turns out that the BEC can not be reached in a bulk and high- density gas and they are searching the BEC in the gas which is magnetically-trapped and thus with a relatively low density.Kyoto University and kurchatov Institute has been working on polarized atomic hydrogen absorbed on liquid helium surface. This hydrogen atoms forms the almost ideal 2-dimensional Bose gas and may become the two-dimensional superfluid (Kosteritz-Thouless Transition). Collaboration between two groups are focused on the search of the K-T transition. Through the collaboration, Kyoto studied cooling mechanisms of two-dimensional hydrogen absorbed on superfluid He and found that hydrogen on ^3He-^4He superfluid film was cooled well down to several 10 mK.kurchatov group investigated hydrogen absorbed on helium films around a strong local magnetic field and found that this hydrogen were very cross to the K-T transition.Now collaboration experiment are setting up at Kyoto for Kyoto's hydrogen equipment by using Kurchatov's mm-ESR equipments. We observed the atomic hydrogen-ESR signal at 127 GHz in Kyoto. In next year, we continue the collaboration and try to detect the two-dimensional hydrogen signal and to search for the K-T transition in this system.