Electron-spin resonance in quantum degenerate 2D atomic hydrogen gas

Abstract

We report on experiments where two-dimensional Bose gas of atomic hydrogen has been compressed thermally on the surface of a small cold spot covered with superfluid helium 4 He at temperatures below 100 mK . The maximum achieved surface densities, up to σ≈5×10 12 cm 2 , are well inside the quantum degeneracy regime with σΛ 2≈1.7. Detection of the adsorbed H↓ atoms in situ by ESR yields direct information on the surface density and temperature profiles across the cold spot and on the mean dipolar field and interatomic interactions in the 2D gas.