Spontaneous population imbalance in two-component Bose and Fermi gases

Abstract

We study two-component (or pseudo-spin-1/2) Bose or Fermi gases in one dimension, in which particles are convertible between the components. Through bosonization and numerical analyses of a simple lattice model, we demonstrate that, in such gases, a strong intercomponent repulsion induces spontaneous population imbalance between the components, namely, the ferromagnetism of the pseudo spins. The imbalanced phase contains gapless charge excitations characterized as a Tomonaga-Luttinger liquid and gapped spin excitations. We uncover a crucial effect of the intercomponent particle hopping on the transition to the imbalanced phase. In the absence of this hopping, the transition is of first order. At the transition point, the energy spectrum reveals certain degeneracy indicative of an emergent SU(2) symmetry. With an infinitesimal intercomponent hopping, the transition becomes of Ising type. We determine the phase diagram of the model accurately and test the reliability of the weak-coupling bosonization formalism.

7 pages, 5 figures

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Cited by in corpus (16)

• One dimensional Bosons: From Condensed Matter Systems to Ultracold Gases
• Entanglement spectra between coupled Tomonaga-Luttinger liquids: Applications to ladder systems and topological phases
• Entanglement entropy between two coupled Tomonaga-Luttinger liquids
• Population-imbalance instability in a Bose-Hubbard ladder in the presence of a magnetic flux
• Equilibrium thermodynamic properties of interacting two-component bosons in one dimension
• Ground state phase diagram of spin-1/2 bosons in a two-dimensional optical lattice
• Breaking of Goldstone modes in two component Bose-Einstein condensate
• Ground-state phase diagram of a spin-1/2 frustrated XXZ ladder
• Magnetic phase diagram and quantum phase transitions in a two-species boson model
• Magnetic phase transition in coherently coupled Bose gases in optical lattices
• Finite temperature phase diagram of spin-1/2 bosons in two-dimensional optical lattice
• Quantum phase transitions and the degree of nonidentity in the system with two different species of vector bosons
• The Bose Hubbard model with squeezed dissipation
• Symmetry, topology, duality, chirality, and criticality in a spin-1/2 XXZ ladder with a four-spin interaction
• Fermionization of a Few-Body Bose System Immersed into a Bose-Einstein Condensate
• Kondo dynamics in one-dimensional doped ferromagnetic insulators