We delineate, as an analog of two-flavor dense quark matter, the phase structure of a many-body mixture of atomic bosons and fermions in two internal states with a tunable boson-fermion attraction. The bosons b correspond to diquarks, and the fermions f to unpaired quarks. For weak b-f attraction, the system is a mixture of a Bose-Einstein condensate and degenerate fermions, while for strong attraction composite b-f fermions N, analogs of the nucleon, are formed, which are superfluid due to the N-N attraction in the spin-singlet channel. We determine the symmetry breaking patterns at finite temperature as a function of the b-f coupling strength, and relate the phase diagram to that of dense QCD.
In spinor Bose Einstein condensates (BEC) gases, a fraction of its thermally excited atoms can still interact with the condensate ground state, leading to spin-spin interactions that can modify the main features of its spin-phase diagrams. In this work we study the spin-phase diagram of a BEC of general spin-
f and fully characterize its noncondensate thermal fraction. The latter provided that the condensate ground state lies within a spin phase with rotational symmetry. The study is based in the Hartree-Fock approximation in conjunction with the Majorana stellar representation approach for pure and mixed quantum states and the use of point-group symmetry arguments. The method allows us to study the phase diagram of spinorial BECs with usual point-group symmetries, including those with some exotic phases associated to the platonic solids (
f=2,3,4, and 6), which are known to lead to non-Abelian topological excitations. In addition, we explore the temperature effects on the admissible spin-phase domains for general spin values, as well as its physical implications on their multipolar magnetic moments.
Motivated by the recent realization of a
52Cr Bose-Einstein condensate, we consider the phase diagram of a general spin-three condensate as a function of its scattering lengths. We classify each phase according to its reciprocal spinor, using a method developed in a previous work. We show that such a classification can be naturally extended to describe the vortices for a spinor condensate by using the topological theory of defects. To illustrate, we systematically describe the types of vortex excitations for each phase of the spin-three condensate.