We study the effective spin models for a Mott insulating Bose-Hubbard model in the presence of gauge fields. We first introduce a simple method based on adiabatic elimination to determine the low-energy effective Hamiltonian. Demonstration of a two-component one-dimensional model with synthetic magnetic field is shown. We further consider a generalized Bose-Hubbard model which covers the cases where spin-orbit coupling and synthetic flux are present. The resulting XYZ model contains Dzyaloshinskii-Moriya interactions and symmetric anisotropic couplings. Under certain conditions, this model reduces to various interesting magnetic Hamiltonians. Phase diagrams for two typical situations are obtained. We investigate magnetic phase transitions by focusing on order parameters and spin-spin correlations. Results are validated by numerical calculations using tensor network algorithms.
We study the effective spin models for a Mott insulating Bose-Hubbard model in the presence of gauge fields. We first introduce a simple method based on adiabatic elimination to determine the low-energy effective Hamiltonian. Demonstration of a two-component one-dimensional model with synthetic magnetic field is shown. We further consider a generalized Bose-Hubbard model which covers the cases where spin-orbit coupling and synthetic flux are present. The resulting XYZ model contains Dzyaloshinskii-Moriya interactions and symmetric anisotropic couplings. Under certain conditions, this model reduces to various interesting magnetic Hamiltonians. Phase diagrams for two typical situations are obtained. We investigate magnetic phase transitions by focusing on order parameters and spin-spin correlations. Results are validated by numerical calculations using tensor network algorithms.
In this paper, we provide a comprehensive study of the quantum magnetism in the Mott insulating phases of the one-dimensional (1D) Bose-Hubbard model with Abelian or non-Abelian synthetic gauge fields, using the density-matrix renormalization-group (DMRG) method. We focus on the interplay between the synthetic gauge field and the asymmetry of the interactions, which give rise to a very general effective magnetic model: an XYZ model with various Dzyaloshinskii-Moriya (DM) interactions. The properties of the different quantum magnetic phases and phases transitions of this model are investigated.
Abstract We investigate the Mott insulating phases of a two-component bosonic lattice gas in the presence of gauge field. Such a system is described by a two-leg ladder model with an unconventional flux. The synthetic flux is generated by the spin-dependent tunneling and the site-dependent spin-flip. In the Mott regime, these two effects lead to Dzyaloshinskii-Moriya (DM) interaction and an external field that is rotating in the xy-plane. We obtain a very general XYZ model with the DM interaction, the spiral field, and the transverse field. Various interesting magnetic Hamiltonians can be covered by adjusting lattice parameters. The DM interaction or the spiral field can lead to spiral order when they appear alone. The interplay of DM coupling and spiral field leads to the emergence of a new multi-frequency spiral order between the paramagnetic phase and the spiral ferromagnetic phase. Ground state phases are investigated by focusing on order parameters, spin-spin correlation functions, and structure factors. Calculations are performed by using time evolution block decimation (TEBD) based on matrix product state (MPS).
Motivated by the experimental realization of synthetic spin-orbit coupling for ultracold atoms, we investigate the phase diagram of the Bose-Hubbard model in a non-Abelian gauge field in two dimensions. Using a strong coupling expansion in the combined presence of spin-orbit coupling and tunable interactions, we find a variety of interesting magnetic Hamiltonians in the Mott insulator (MI), which support magnetic textures such as spin spirals and vortex and Skyrmion crystals. An inhomogeneous mean-field treatment shows that the superfluid (SF) phases inherit these exotic magnetic orders from the MI and display, in addition, unusual modulated current patterns. We present a slave-boson theory which gives insight into such intertwined spin-charge orders in the SF, and discuss signatures of these orders in Bragg scattering, in situ microscopy, and dynamic quench experiments.
We explore the Mott insulating phases of dual-species bosonic spinor lattice gases, emphasizing the intriguing interplay between synthetic flux and inter-species spin exchange interaction. One of the species is subjected to Raman assisted tunneling, which leads to a synthetic flux within the framework of synthetic dimensions. In the deep Mott regime, the low energy physics is governed by an unconventional and highly tunable spin model, which is characterized by two distinct spin chains. The synthetic flux serves as an effective spin-orbit coupling, inducing Dzyaloshinskii-Moriya interactions in one of the spin chains. The inter-species spin exchange interaction gives rise to the inter-chain coupling embodied as an isotropic XX interaction. Using time-evolving block decimation method for tensor network states, we compute order parameters, correlation functions and structure factors to identify the ground state magnetic phases. The DM interaction in one species, when combined with the inter-species spin-exchange interaction, can induce spiral magnetic order in the second, otherwise non-chiral species. Besides, the interplay of a transverse field applied to one spin chain and the inter-species coupling can drive both spin chains into a paramagnetic phase simultaneously. These results reveal that inter-species coupling serves as a powerful conduit for transmitting magnetic correlations, enabling exotic phases beyond the single-component perspective.
We consider effects of artificial magnetic fields on the ground state of the two-dimensional Bose-Hubbard model. Using an asymmetric Bose-Hubbard model, we demonstrate that the frustrating hopping energy localizes bosons and enlarges insulators and supersolid borders. We show these increments in the presence of artificial gauge fields up to a symmetric point of the field. Moreover, our calculations exhibit the real space modulations of the superfluid and supersolid phases. The bosonic current exhibits vortices in these phases, which their configurations depend on the commensuration between the magnetic field and the lattice. Although the magnetic field breaks the translational symmetry of the square lattice explicitly, this symmetry is restored in the Mott insulator phase. The filling factor exhibits a checkerboard pattern in the density-wave and supersolid phases, regardless of the magnetic field strength. We explore thermal fluctuations and demonstrate the robustness of insulators and SS phases up to temperatures comparable to the interaction energy, which support the feasibility of observing such phases in experiments.
We study the effects of an artificial gauge field on the ground-state phases of the Bose-Hubbard model on a checkerboard superlattice in two dimensions, including the superfluid phase and the Mott and alternating Mott insulators. First, we discuss the single-particle Hofstadter problem, and show that the presence of a checkerboard superlattice gives rise to a magnetic flux-independent energy gap in the excitation spectrum. Then, we consider the many-particle problem, and derive an analytical mean-field expression for the superfluid-Mott and superfluid--alternating-Mott insulator phase transition boundaries. Finally, since the phase diagram of the Bose-Hubbard model on a checkerboard superlattice is in many ways similar to that of the extended Bose-Hubbard model, we comment on the effects of magnetic field on the latter model, and derive an analytical mean-field expression for the superfluid-insulator phase transition boundaries as well.