Scaling of the polarization amplitude in quantum many-body systems in one dimension

Article

关键词: MECHANICAL POSITION-OPERATOR;    EXTENDED SYSTEMS;    INSULATING STATE;    GROUND-STATE;    XXZ CHAIN;    PHASE;    LOCALIZATION;    SOLIDS;   

DOI  :  10.1103/PhysRevB.97.165133

来源: SCIE

【 摘 要 】

Resta proposed a definition of the electric polarization in one-dimensional systems in terms of the ground-state expectation value of the large gauge transformation operator. Vanishing of the expectation value in the thermodynamic limit implies that the system is a conductor. We study Resta's polarization amplitude (expectation value) in the S = 1/2 XXZ chain and its several generalizations, in the gapless conducting Tomonaga-Luttinger liquid phase. We obtain an analytical expression in the lowest-order perturbation theory about the free fermion point (XY chain) and an exact result for the Haldane-Shastry model with long-range interactions. We also obtain numerical results, mostly using the exact diagonalization method. We find that the amplitude exhibits a power-law scaling in the system size (chain length) and vanishes in the thermodynamic limit. On the other hand, the exponent depends on the model even when the low-energy limit is described by the Tomonaga-Luttinger liquid with the same Luttinger parameter. We find that a change in the exponent occurs when the Umklapp term(s) are eliminated, suggesting the importance of the Umklapp terms.

【 授权许可】

Free