Summation of Divergent Series and Quantum Phase Transitions in Kitaev Chains with Long-Range Hopping

Fuente: arXiv
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Autori principali: Fu, Hao, Tong, Peiqing
Natura: Preprint
Pubblicazione: 2023
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author Fu, Hao
Tong, Peiqing
author_facet Fu, Hao
Tong, Peiqing
contents We study the quantum phase transitions (QPTs) in extended Kitaev chains with long-range ($1/r^α$) hopping. Formally, there are two QPT points at $μ=μ_0(α)$ and $μ_π(α)$ ($μ$ is the chemical potential) which correspond to the summations of $\sum_{m=1}^{\infty}m^{-α}$ and $\sum_{m=1}^{\infty}(-1)^{m-1}m^{-α}$, respectively. When $α\leq0$, both the series are divergent and it is usually believed that no QPTs exist. However, we find that there are two QPTs at $μ=μ_0(0)$ and $μ_π(0)$ for $α=0$ and one QPT at $μ=μ_π(α)$ for $α<0$. These QPTs are second order. The $μ_0(0)$ and $μ_π(α\leq0)$ correspond to the summations of the divergent series obtained by the analytic continuation of the Riemann $ζ$ function and Dirichlet $η$ function. Moreover, it is found that the quasiparticle energy spectra are discontinue functions of the wave vector $k$ and divide into two branches. This is quite different from that in the case of $α>0$ and induces topological phases with the winding number $ω:=\pm1/2$. At the same time, the von Neumann entropy are power law of the subchain length $L$ no matter in the gapped region or not. In addition, we also study the QPTs, topological properties, and von Neumann entropy of the systems with $α>0$.
format Preprint
id arxiv_https___arxiv_org_abs_2312_09566
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Summation of Divergent Series and Quantum Phase Transitions in Kitaev Chains with Long-Range Hopping
Fu, Hao
Tong, Peiqing
Statistical Mechanics
We study the quantum phase transitions (QPTs) in extended Kitaev chains with long-range ($1/r^α$) hopping. Formally, there are two QPT points at $μ=μ_0(α)$ and $μ_π(α)$ ($μ$ is the chemical potential) which correspond to the summations of $\sum_{m=1}^{\infty}m^{-α}$ and $\sum_{m=1}^{\infty}(-1)^{m-1}m^{-α}$, respectively. When $α\leq0$, both the series are divergent and it is usually believed that no QPTs exist. However, we find that there are two QPTs at $μ=μ_0(0)$ and $μ_π(0)$ for $α=0$ and one QPT at $μ=μ_π(α)$ for $α<0$. These QPTs are second order. The $μ_0(0)$ and $μ_π(α\leq0)$ correspond to the summations of the divergent series obtained by the analytic continuation of the Riemann $ζ$ function and Dirichlet $η$ function. Moreover, it is found that the quasiparticle energy spectra are discontinue functions of the wave vector $k$ and divide into two branches. This is quite different from that in the case of $α>0$ and induces topological phases with the winding number $ω:=\pm1/2$. At the same time, the von Neumann entropy are power law of the subchain length $L$ no matter in the gapped region or not. In addition, we also study the QPTs, topological properties, and von Neumann entropy of the systems with $α>0$.
title Summation of Divergent Series and Quantum Phase Transitions in Kitaev Chains with Long-Range Hopping
topic Statistical Mechanics
url https://arxiv.org/abs/2312.09566