The quantum phase of hard-core bosons in Creutz ladder with zero flux is studied. For a specific regime of the parameters （tx = tp,ty 〈 0）, the exact ground-state is found analytically, which is a dimerized insulat...The quantum phase of hard-core bosons in Creutz ladder with zero flux is studied. For a specific regime of the parameters （tx = tp,ty 〈 0）, the exact ground-state is found analytically, which is a dimerized insulator with one electron bound in each rung of the ladder. For the case tx, ty, tp 〉 0, the system is exactly studied using quantum Monte Carlo （QMC） method without a sign problem. It is found that the system is a Mott insulator for small tp and a quantum phase transition to a superfluid phase is driven by increasing tp. The critical t~ is determined precisely by a scaling analysis. Since it is possible that the Creutz ladder is realized experimentally, the theoretical results are interesting to the cold-atom experiments.展开更多
We study topological properties of the one-dimensional Creutz ladder model with different non-Hermitian asymmetric hoppings and on-site imaginary potentials,and obtain phase diagrams regarding the presence and absence...We study topological properties of the one-dimensional Creutz ladder model with different non-Hermitian asymmetric hoppings and on-site imaginary potentials,and obtain phase diagrams regarding the presence and absence of an energy gap and in-gap edge modes.The non-Hermitian skin effect(NHSE),which is known to break the bulk-boundary correspondence(BBC),emerges in the system only when the non-Hermiticity induces certain unbalanced non-reciprocity along the ladder.The topological properties of the model are found to be more sophisticated than that of its Hermitian counterpart,whether with or without the NHSE.In one scenario without the NHSE,the topological winding is found to exist in a two-dimensional plane embedded in a four-dimensional space of the complex Hamiltonian vector.The NHSE itself also possesses some unusual behaviors in this system,including a high spectral winding without the presence of long-range hoppings,and a competition between two types of the NHSE,with the same and opposite inverse localization lengths for the two bands,respectively.Furthermore,it is found that the NHSE in this model does not always break the conventional BBC,which is also associated with whether the band gap closes at exceptional points under the periodic boundary condition.展开更多
The spin-3/2 Ising model on the simple cubic lattice with nearest-neighbour ferromagnetic bilinear interaction(J>0)is simulated on a cellular automaton by using the cooling algorithm improved from the Creutz cellul...The spin-3/2 Ising model on the simple cubic lattice with nearest-neighbour ferromagnetic bilinear interaction(J>0)is simulated on a cellular automaton by using the cooling algorithm improved from the Creutz cellular automaton.The phase diagrams of the model are constructed in the(D/J,kT/J)and(K/J,kT/J)plane.Comparison of the results are made with those of other methods.The temperature dependence of the order parameters and associated fluctuations are calculated at various of the model parameters and the static critical exponents are estimated within the framework of the finite-size scaling.The results are compatible with the universal Ising critical behavior except for D/J=−3 and K/J=−2.3.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274032,11774019,51472016,and 51672018)
文摘The quantum phase of hard-core bosons in Creutz ladder with zero flux is studied. For a specific regime of the parameters （tx = tp,ty 〈 0）, the exact ground-state is found analytically, which is a dimerized insulator with one electron bound in each rung of the ladder. For the case tx, ty, tp 〉 0, the system is exactly studied using quantum Monte Carlo （QMC） method without a sign problem. It is found that the system is a Mott insulator for small tp and a quantum phase transition to a superfluid phase is driven by increasing tp. The critical t~ is determined precisely by a scaling analysis. Since it is possible that the Creutz ladder is realized experimentally, the theoretical results are interesting to the cold-atom experiments.
文摘We study topological properties of the one-dimensional Creutz ladder model with different non-Hermitian asymmetric hoppings and on-site imaginary potentials,and obtain phase diagrams regarding the presence and absence of an energy gap and in-gap edge modes.The non-Hermitian skin effect(NHSE),which is known to break the bulk-boundary correspondence(BBC),emerges in the system only when the non-Hermiticity induces certain unbalanced non-reciprocity along the ladder.The topological properties of the model are found to be more sophisticated than that of its Hermitian counterpart,whether with or without the NHSE.In one scenario without the NHSE,the topological winding is found to exist in a two-dimensional plane embedded in a four-dimensional space of the complex Hamiltonian vector.The NHSE itself also possesses some unusual behaviors in this system,including a high spectral winding without the presence of long-range hoppings,and a competition between two types of the NHSE,with the same and opposite inverse localization lengths for the two bands,respectively.Furthermore,it is found that the NHSE in this model does not always break the conventional BBC,which is also associated with whether the band gap closes at exceptional points under the periodic boundary condition.
基金This work was supported by the Scientific and Technological Research Council of Turkey(T¨UB˙ITAK)Grant no:109T018.
文摘The spin-3/2 Ising model on the simple cubic lattice with nearest-neighbour ferromagnetic bilinear interaction(J>0)is simulated on a cellular automaton by using the cooling algorithm improved from the Creutz cellular automaton.The phase diagrams of the model are constructed in the(D/J,kT/J)and(K/J,kT/J)plane.Comparison of the results are made with those of other methods.The temperature dependence of the order parameters and associated fluctuations are calculated at various of the model parameters and the static critical exponents are estimated within the framework of the finite-size scaling.The results are compatible with the universal Ising critical behavior except for D/J=−3 and K/J=−2.3.
