Finite-size scaling of the Shannon-Renyi entropy in two-dimensional systems with spontaneously broken continuous symmetry

Article

关键词: BOSONS;   

DOI  :  10.1103/PhysRevB.95.195161

来源: SCIE

【 摘 要 】

We study the scaling of the (basis-dependent) Shannon entropy for two-dimensional quantum antiferromagnets with Neel long-range order. We use a massless free-field description of the gapless spin wave modes and phase space arguments to treat the fact that the finite-size ground state is rotationally symmetric, while there are degenerate physical ground states which break the symmetry. Our results show that the Shannon entropy (and its Renyi generalizations) possesses some universal logarithmic term proportional to the number N-NG of Nambu-Goldstone modes. In the case of a torus, we show that S-n > 1 similar or equal to const. x N + N-NG/4 n/n-1 ln N and S-1 similar or equal to const. x N - N-NG/4 ln N, where N is the total number of sites and n the Renyi index. The result for n > 1 is in reasonable agreement with the quantum Monte Carlo results of Luitz et al. [Phys. Rev. Lett. 112, 057203 (2014)], and qualitatively similar to those obtained previously for the entanglement entropy. The Shannon entropy of a line subsystem (embedded in the two-dimensional system) is also considered. Finally, we present some density-matrix renormalization group (DMRG) calculations for a spin-1/2 XY model on the square lattice in a cylinder geometry. These numerical data confirm our findings for logarithmic terms in the n = infinity Renyi entropy (also called - ln p(max)). They also reveal some universal dependence on the cylinder aspect ratio, in good agreement with the fact that, in that case, p(max) is related to a noncompact free-boson partition function in dimension 1 + 1.

【 授权许可】

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