Fangyu Xiong | Searcharxiv

arXiv2026

Projected Holstein-Primakoff boson representation of quantum spins for spin wave theory

The Holstein-Primakoff boson representation of quantum spins and associated large-$S$ expansion have been the standard framework for describing the spin wave excitations in magnetically order phases of quantum spin systems. However, we will show that the omission of projection operators and normal-ordering in this representation can produce incorrect magnon hamiltonians for finite $S$. We will present the exact normal-ordered forms of the finite-$S$ projection operators and projected Holstein-Primakoff boson representations of spin and quadrupole operators, which can produce exact two-magnon interaction terms under ferromagnetic or fully polarized states. We will also discuss the difficulties of applying this projected representation to antiferromagnetic spin wave theory.

cond-mat.str-el↗

arXiv2020

Simulation of Dynamical Quantum Phase Transition of the 1D Transverse Ising Model with a Double-chain Bose-Hubbard model

We propose a spinless Bose-Hubbard model in an one-dimensional (1D) double-chain tilted lattice at unit filling per cell. A subspace of this model can be faithfully mapped to the 1D transverse Ising model through superexchange interaction with second-order perturbation theory. At a valid parameter region, numerical results show good agreement of these two models both on energy spectrums and correlation functions. And we show that the dynamical quantum phase transition of the effective 1D transverse Ising model can be simulated. With carefully designed procedures for producing the dynamical quantum phase transition of the 1D transverse Ising model from a Mott insulator, the rate function of the recurrence probability to the ground-state manifold shows the same nonanalyticality at periodic time points as theory predicts. Our results may give some inspirations on simulating 1D transverse Ising model with superexchange interaction and exploring its dynamical quantum phase transition in experiment.

cond-mat.quant-gas↗