Confinement of gaseous atoms with superfluid helium film and its application to the test of time-reversal symmetry

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The purpose of this project is to realize the alkali vapor cell at liquid helium temperature, by coating the cell walls with superfluid helium film, suitable for the spin- related fundamental physics, particularly to the measurement of atomic electric dipole moment (EDM) for the test of time reversal symmetry. Through this project we could get various important results as follows.(1) We could realize experimentally alkali vapor cell, where the life of gaseous alkali atoms was as long as 10-100 s.(2) We could develop a novel method of production of alkali gaseous atoms, so called "light-induced atom desorption LIAD" method, witch can produce gaseous atoms with weak cw light, without strong convection.(3) It was found that the superfluidity of the liquid helium on the wall plays an important role for the LIAD, and the mechanism could be revealed.(4) Optical pumping experiment was made to the produced atoms in the cold cell. We found that the spin-relaxation time was determined by the lifetime of atoms 10-100 s.(5) We developed the method of atomic spin with the Faraday effect, which minimized the perturbation to the spin state. We also proposed the method of spin non-demolition measurement, which is very suitable for the atomic EDM measurement.(7) We also proposed and studied a novel method to observe the special distribution of spin polarization, optical magnetic-resonance imaging.(8) As a new effect of cold helium gas to alkali-metal atom, we found the formation of excimer and exciplexes, where helium atoms are sticking to the excited state alkali atoms. Trough spectroscopic studies of these excited-state molecules, we could determine their energies, including vibrational energies, and could get the information of formation.