理论预言的超固体是一种新奇物质态。Chan小组否定其04年发现的氦超固体，原因是多孔玻璃盘实验装置不理想。光晶格是无杂质无缺陷的理想实验平台，在光晶格中的冷原子系统中寻找新型超固体，揭示其存在机制、相变等量子规律具有重要理论和实验意义。目前人们主要在软硬核、多组分或配对扩展的玻色哈伯德模型和自旋系统中研究超固体，并总结出三条超固体形成机制：有序无序、掺杂和无需掺杂。为了寻找新超固体并探索其存在机制，本项目拟模拟含新隧穿特征的玻色哈伯德模型：阻挫配对隧穿、三体隧穿和自旋翻转隧穿玻色哈伯德模型。我们运用的方法是自行改进的量子蒙特卡罗方法，辅助以密度矩阵重整化群和Gutzwiller平均场方法。在前期预研究中，我们发现阻挫配对超固体和三体隧穿超流体的存在证据，并找到自旋翻转隧穿玻色子的模拟方案。本申请项目的研究结果将促进发展更准确的平均场方法，有助于理解超固体并指导光晶格实验探索超固体。

The supersolid theoretically predicted is a novel state of matter. M.Chan team deny supersolid He they found in the year 2004 because the experimental configuration of porous vycor glass disc is imperfect. The optical lattice is an idea experimental platform free of impurities and defects, therefore, exploring the new types of supersolid in the optical lattice is of theoretical and experimental significances to revealing the quantum laws such as the mechanism of existence of supersolid and the phase transitions. At present, supersolid is explored in soft- core or hard-core, multi-component, pair tunneling extended bose-hubbard models and spin systems , in which three mechanisms are discovered: order by disorder, doping and without doping. In order to find new types of supersolid and their mechanisms, in this project, we plan to search supersolid with new properties of tunneling in extended bose-hubbard models, which include frustrated pair tunneling, three-body tunneling and spin-flip tunneling extended bose-hubbard models. The method we use is self-improved Quantum Monte Carlo method with Density Matrix Renormalization Group method and Gutzwiller mean-field method serving as supplementary methods. We preliminary at the early stage find the evidences of the frustrated-pair tunneling supersolid and three-body tunneling superfluid and the scheme to simulate bosons with spin-flip tunneling.The research results will promote the development of more precise mean-field methods and guide for understatnding and detecting novel states of matter such as supersolid in optical lattice experiment.