Spin-polarized hydrogen and its isotopes: A rich class of quantum phases (Review Article)

Abstract

We review the recent activity in the theoretical description of spin-polarized atomic hydrogen and its isotopes at very low temperatures. Spin-polarized hydrogen is the only system in nature that remains stable in the gas phase even in the zero temperature limit due to its small mass and weak interatomic interaction. Hydrogen and its heavier isotope tritium are bosons, the heavier mass of tritium producing a self-bound (liquid) system at zero temperature. The other isotope, deuterium, is a fermion with nuclear spin one making possible the study of three different quantum systems depending on the population of the three degenerate spin states. From the theoretical point of view, spin-polarized hydrogen is specially appealing because its interatomic potential is very accurately known making possible its precise quantum many-body study. The experimental study of atomic hydrogen has been very difficult due to its high recombination rate, but it finally led to its Bose-Einstein condensate state in 1998. Degeneracy has also been observed in thin films of hydrogen adsorbed on the 4 He surface allowing for the possibility of observing the Berezinskii-Kosterlitz-Thouless superfluid transition. PACS: 64.60.Bd General theory of phase transitions; 67.63.Gh Atomic hydrogen and isotopes; 67.85.Jk Other Bose-Einstein condensation phenomena.

One dimensional1H,2H and3H

“…The JDW potential exhibits an attractive well with a minimum of −6.49K at x=4.14 Å and has a repulsive hard wall at short distances. This potential was used to predict ground-state properties and stability of bulk and clusters of hydrogen, deuterium, and tritium [16,[22][23][24]. We study the 1D homogeneous system by applying periodic boundary conditions to a box of length L. We are interested in the microscopic properties of the system in the thermodynamic limit at a given linear density ρ=N/L.…”

“…A further advantage of considering polarized hydrogen is that its interatomic potential is exactly known from works by Kolos, Jamieson, Dalgarno, and Wolniewicz [12,13,14]. As the model potential is the only input of quantum Monte Carlo methods, we can benefit of its power for producing very accurate quantitative results [15][16][17][18][19].…”

Impact of Warm Dark Matter on the Cosmic Neutrino Background Anisotropies

“…The possibility of a superfluid ground-state condensate of spin-polarized tritium atoms may provide an amplification mechanism for the process of relic neutrino capture. Spin-polarized tritium atoms, which are neutral bosons, have long been considered an ideal candidate to form a quantum liquid [9]. The lightest spin-polarized hydrogen isotope in a gaseous phase was successfully cooled down in a magnetic trap to form a Bose-Einstein Condensate in 1998 [10].…”

Impact of Warm Dark Matter on the Cosmic Neutrino Background Anisotropies

“…The possibility of a superfluid ground-state condensate of spin-polarized tritium atoms may provide an amplification mechanism for the process of relic neutrino capture. Spin-polarized tritium atoms, which are neutral bosons, have long been considered an ideal candidate to form a quantum liquid [8]. The lightest spin-polarized hydrogen isotope in a gaseous phase was successfully cooled down in a magnetic trap to form a Bose-Einstein Condensate in 1998 [9].…”