We explore the effects of geometric frustration within a one-dimensional Bose-Hubbard model using a chain of rhombi subject to a magnetic flux. The competition of tunnelling, self-interaction and magnetic flux gives rise to the emergence of a pair-superfluid (pair-Luttinger liquid) phase besides the more conventional Mott-insulator and superfluid (Luttinger liquid) phases. We compute the complete phase diagram of the model by identifying characteristic properties of the pair-Luttinger liquid phase such as pair correlation functions and structure factors and find that the pair-Luttinger liquid phase is very sensitive to changes away from perfect frustration (half-flux). We provide some proposals to make the model more resilient to variants away from perfect frustration. We also study the bipartite entanglement properties of the chain. We discover that, while the scaling of the block entropy pair-superfluid and of the single-particle superfluid leads to the same central charge, the properties of the low-lying entanglement spectrum levels reveal their fundamental difference.
Bosonic Working Media in a Frustrated Rhombi Chain: Otto and Stirling Cycles from Flat Bands, Caging, and Flux Control
Facultad de Ingeniería, Universidad San Sebastián（圣塞巴斯蒂安大学工程学院）；Departamento de Física, Universidad Técnica Federico Santa María（智利技术费德里科·萨马拉大学物理系）；Department of Physics, Universitat Autònoma de Barcelona（巴塞罗那自治大学物理系）；Instituto de Física, Pontificia Universidad Católica de Valparaíso（天主教瓦尔帕莱索大学物理研究所）；Physical and Computational Sciences,Pacific Northwest National Laboratory（太平洋西北国家实验室物理与计算科学部）；Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile（智利大学物理与数学科学学院物理系）
Nagaoka supermetal in the particle-doped triangular Hubbard model
College of Science, National University of Defense Technology（国防科技大学理学院）；Institute of Modern Physics, Northwest University（西北大学现代物理研究所）；Hefei National Laboratory（合肥国家实验室）；Institute of Atomic and Molecular Physics, Jilin University（吉林大学原子与分子物理研究所）
