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The values of the insulator gap Δ in one-dimensional systems of interacting bosons described by the Hubbard Hamiltonian are
calculated at low temperatures by the quantum world-line Monte Carlo algorithm. The dependence of Δ on the size of the system,
the temperature, and the parameters of the model is investigated. It is shown that a chain with N
a=50 sites is already sufficient to estimate the thermodynamic value of the critical quantity (t/U)c for which a transition from the insulator into the superfluid state occurs in a commensurate system. To within the computational
error, this value, (t/U)c=0.300±0.005, agrees with the value (t/U)c=0.304±0.002 obtained previously by the combined “exact diagonalization + renormalization-group analysis” method. The characteristic
Kosterlitz-Thouless behavior of the insulator gap is demonstrated near the critical region: Δ∼exp[−b(1−t/t
c)−1/2].
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 2, 92–96 (25 July 1996) 相似文献
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《Physics letters. A》2014,378(38-39):2894-2899
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运用约束路径量子蒙特卡罗方法,对二维、三带Hubbard模型中的环形电流相进行数值模拟。在数值模拟过程中定义了表征环流相的不同算符及其关联函数,并且选用合理的模型Hamiltonian量中的参数。通过模拟发现,对应于闭合环形的关联函数在相同距离上要比其他所有没有闭合的关联函数大得多,因此证明在三带Hubbard模型中存在环形电流相。 相似文献
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Meshkov SV 《Physical review. B, Condensed matter》1993,48(9):6167-6178
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The one dimensional Hubbard model with nearest and (negative) next-nearest neighbour hopping has been studied with the density-matrix renormalization group (DMRG) method. A large region of ferromagnetism has been found for finite density and finite on-site interaction. 相似文献
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Al-Hassanieh KA Reboredo FA Feiguin AE González I Dagotto E 《Physical review letters》2008,100(16):166403
We study the real-time dynamics of a hole and doubly occupied site pair, namely, a holon and a doublon, in a 1D Hubbard insulator with on-site and nearest-neighbor Coulomb repulsion. Our analysis shows that the pair is long-lived and the expected decay mechanism to underlying spin excitations is actually inefficient. For a nonzero intersite Coulomb repulsion, we observe that part of the wave function remains in a bound state. Our study also provides insight on the holon-doublon propagation in real space. Because of the one-dimensional nature of the problem, these particles move in opposite directions even in the absence of an applied electric field. The potential relevance of our results to solar cell applications is discussed. 相似文献
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Guo-Feng Zhang Heng Fan Ai-Ling Ji Zhao-Tan Jiang Ahmad Abliz Wu-Ming Liu 《Annals of Physics》2011,326(10):2694-2701
Bell nonlocality, entanglement and nonclassical correlations are different aspects of quantum correlations for a given state. There are many methods to measure nonclassical correlations. In this paper, nonclassical correlations in two-qubit spin models are measured by the use of measurement-induced disturbance (MID) [S. Luo, Phys. Rev. A 77 (2008) 022301] and geometric measure of quantum discord (GQD) [B. Daki?, V. Vedral, C. Brukner, Phys. Rev. Lett. 105 (2010) 190502]. Their dependences on external magnetic field, spin–spin coupling, and the Dzyaloshinskii–Moriya (DM) interaction are presented in detail. We also compare Bell nonlocality, entanglement measured by concurrence, MID and GQD and illustrate their different characteristics. 相似文献
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This paper presents the results of stationary-phase Monte Carlo simulations for the dynamics of the spin-boson problem. The problem of alternating weights ubiquitous in dynamical simulations has been solved using discretized path-integral simulations in conjunction with stationary-phase filtering techniques. Our computation covers the bulk of the parameter space, including non-zero bias and frequency-dependent dissipation. Besides a comparison with analytic predictions, we present some new results. For sub-Ohmic dissipation, the dynamics at low temperatures depends significantly on the initial preparation. In the Ohmic regime 1/2<K<1, whereK is Kondo's dimensionless coupling strength, we find significant deviations from the predictions of the non-interacting blip approximation at long times and low temperatures. 相似文献