Boson-Mixtures at Non-Zero Temperatures

Henrik Smith, Luciano Viverit, C. J. Pethick

MANFRED L. RISTIG, Stefano Fantoni, K. E. K�rten

Michael David Miller

We investigate the thermodynamic ground state of binary boson mixtures using a variational ansatz. With a pair-independent trial function we map the isotopic boson mixture onto a quantum theorem of corresponding-states picture which enables us to conclude that all such isotopic boson mixtures completely phase-separate at zero temperature. We also investigate mixtures of spin-aligned hydrogen (H\ensuremath{\uparrow}) and spin-aligned tritium (T\ensuremath{\uparrow}) with $^{4}\mathrm{He}$. We find that these systems also prefer to completely phase-separate. However, due to important differences in the sizes of "cores" of the interaction, allowance must be made for different correlations between different types of pairs. We then find that at zero pressure the zero-concentration chemical potential for H\ensuremath{\uparrow} in $^{4}\mathrm{He}$ is 40 K and for T\ensuremath{\uparrow} in $^{4}\mathrm{He}$ it is 0.5 K.

Tapash Chakraborty

Luciano Viverit, C. J. Pethick, H. Smith

We calculate the phase diagram for dilute mixtures of bosons and fermions at zero temperature. The linear stability conditions are derived and related to the effective boson-induced interaction between the fermions. We show that in equilibrium there are three possibilities: (a) a single uniform phase, (b) a purely fermionic phase coexisting with a purely bosonic one, and (c) a purely fermionic phase coexisting with a mixed phase.

X. X. Yi, C. P. Sun

Phase separation of a Bose-Fermi gas mixture in a trapping potential is strongly influenced by the interaction between the fermion and the boson. The stability condition for the mixture at zero temperature is deduced. It is found that mixture stability depends on the fermion-boson interaction, the total number of the bosons and the fermions, and the trapping frequencies. The stability conditions for the mixture at finite temperature are also derived and discussed.