Some macroscopic quantum effects in rarefied molecular gases

Giovanni Gallavotti, Joel L. Lebowitz, Vieri Mastropietro

Eugene P. Bashkin, Oleg L. Puzyrko

A new branch of weakly damped collective magnetic excitations in spin-polarized low-density systems is predicted. This type of wave corresponds to the transverse oscillations of the macroscopic quadrupole moment while the magnetization does not oscillate. The spectra of both spin waves and quadrupole modes are calculated. The theory can be applied to gaseous H\ensuremath{\downarrow}, D\ensuremath{\downarrow}, and other rarefied gases of S=1 particles.

Georgy V. Shlyapnikov

S. A. Trigger

An expression for the short-range effective interaction potential of “quasinuclei” is derived based on the “pure” Coulomb interaction model. This model represents the equilibrium Coulomb system (CS) of interacting electrons and identical nuclei using the adiabatic approximation for nuclei and an arbitrarily strong (in general) interaction for the electronic subsystem (degenerate or nondegenerate). Based on general properties of the Coulomb interaction, it is shown that the Fourier component of the effective pair potential between “quasinuclei” is discontinuous at the wave vector q = 0 in the case of the weak interaction between electronic and nuclear subsystems. This discontinuity is important for Bose-condensed systems such as Hell and rarefied alkali-metal gases at temperatures lower than that of the Bose condensation transition when a macroscopic number of quasiparticles with momentum q = 0 exist. It is shown that there can be a spectral gap for single-particle excitations, which disappears in the normal state.

Kang-Kuen Ni