arXiv subjects

Dániel Vörös

Publications and source records attributed to Dániel Vörös.

4 recordsLinked to original sources

arXiv2025

The algebraic spin liquid in the SU(6) Heisenberg model on the kagome lattice

We explore the Dirac spin liquid (DSL) as a candidate for the ground state of the Mott insulating phase of fermions with six flavors on the Kagome lattice, particularly focusing on realizations using $^{173}$Yb atoms in optical lattices. Using mean-field theory and variational Monte Carlo simulations, we demonstrate that the Dirac spin liquid (DSL) has the lowest variational energy among SU(6) symmetry-preserving trial wave functions with a periodicity of a 12-site unit cell, as well as uniform chiral states with larger unit cells. It remains a local minimum even when small second-nearest neighbor and ring exchange interactions are introduced. To characterize the DSL, we calculate the static and dynamic structure factor of the Gutzwiller projected wavefunction and compare it with mean-field calculations. The static structure factor shows triangular-shaped plateaus around the $\mathrm{K}$ points in the extended Brillouin zone, with small peaks at the corners of these plateaus. The dynamical structure factor consists of a gapless continuum of fractionalized excitations. Our study also presents several complementary results, including bounds for the ground state energy, methods for calculating three-site ring exchange expectations in the projective mean field, the boundary of ferromagnetic states, and the non-topological nature of flat bands in the DSL band structure.

cond-mat.str-el↗

arXiv2024

The dynamical structure factor of the SU(4) algebraic spin liquid on the honeycomb lattice

We compute the momentum resolved dynamical spin structure factor $S(k,ω)$ of the SU(4) Heisenberg model on the honeycomb lattice assuming the $π$-flux Dirac spin liquid ground state by two methods: (i) variationally using Gutzwiller projected particle-hole excitations of the $π$-flux Fermi sea and (ii) in the non-interacting parton mean-field picture. The two approaches produce qualitatively similar results. Based on this analogy, we argue that the energy spectrum of the projected excitations is a gapless continuum of fractional excitations. Quantitatively, the Gutzwiller projection shifts the weight from higher to lower energies, thus emphasizing the lower edge of the continuum. In the mean-field approach, we obtained the $1/\text{distance}^4$ decay of the spin correlation function, and the local correlations show $S^{33}_{\text{MF}}(ω)\propto ω^3$ behavior.

cond-mat.str-el↗

arXiv2022

Finite temperature dynamics in gapped 1D models in the sine-Gordon family

The sine-Gordon model appears as the low-energy effective field theory of various one-dimensional gapped quantum systems. Here we investigate the dynamics of generic, non-integrable systems belonging to the sine-Gordon family at finite temperature within the semiclassical approach. Focusing on time scales where the effect of nontrivial quasiparticle scatterings becomes relevant, we obtain universal results for the long-time behavior of dynamical correlation functions. We find that correlation functions of vertex operators behave neither ballistically nor diffusively but follow a stretched exponential decay in time. We also study the full counting statistics of the topological current and find that distribution of the transferred charge is non-Gaussian with its cumulants scaling non-uniformly in time.

cond-mat.stat-mech↗

arXiv2022

The dynamical structure factor of the SU(3) Heisenberg chain: The variational Monte Carlo approach

We compute the dynamical spin structure factor $S(k,ω)$ of the SU(3) Heisenberg chain variationally using a truncated Hilbert space spanned by the Gutzwiller projected particle-hole excitations of the Fermi sea, introduced in [B. Dalla Piazza et al., Nature Physics 11, 62 (2015)], with a modified importance sampling. We check the reliability of the method by comparing the $S(k,ω)$ to exact diagonalization results for 18 sites and to the two-soliton continuum of the Bethe Ansatz for 72 sites. We get an excellent agreement in both cases. Detailed analysis of the finite-size effects shows that the method captures the critical Wess-Zumino-Witten SU(3)$_1$ behavior and reproduces the correct exponent, with the exception of the size dependence of the weight of the bottom of the conformal tower. We also calculate the single-mode approximation for the SU($N$) Heisenberg model and determine the velocity of excitations. Finally, we apply the method to the SU(3) Haldane-Shastry model and find that the variational method gives the exact wave function for the lowest excitation at $k=\pm 2π/3$.

cond-mat.str-el↗