Role of single-particle and pair condensates in Bose systems with arbitrary intensity of interaction

• Main Authors: Peletminskii, A. S, Peletminskii, S. V, Poluektov, Yu. M
• Format: Journal Article
• Language: English
• Published: 22-03-2013
• Subjects: Physics - Quantum Gases; Physics - Statistical Mechanics
• DOI: 10.48550/arxiv.1303.5539

Condens. Matter Phys., 2013, vol. 16, No. 1, 13603:1-17 We study a superfluid Bose system with single-particle and pair condensates
on the basis of a half-phenomenological theory of a Bose liquid not involving
the weakness of interparticle interaction. The coupled equations describing the
equilibrium state of such system are derived from the variational principle for
entropy. These equations are analyzed at zero temperature both analytically and
numerically. It is shown that the fraction of particles in the single-particle
and pair condensates essentially depends on the total density of the system. At
densities attainable in condensates of alkali-metal atoms, almost all particles
are in the single-particle condensate. The pair condensate fraction grows with
an increasing total density and becomes dominant. It is shown that at density
of liquid helium, the single-particle condensate fraction is less than 10%,
which agrees with experimental data on inelastic neutron scattering, Monte
Carlo calculations and other theoretical predictions. The ground state energy,
pressure, and compressibility are found for the system under consideration. The
spectrum of single-particle excitations is also analyzed.