单组分和双组分玻色-哈伯德模型基态和温度特性的标准基算子方法
Standard basis operator method for ground-state and temperature properties of single and two-component Bose-Hubbard model
AI总结：
针对三维单组分和双组分玻色-哈伯德模型，提出改进的标准基算子方法，单组分中考虑更多在位态增强预测并改善计算性能，双组分推广性差但仍预测了相图变形及相变。
AI中文摘要：
我们为三维单组分和双组分玻色-哈伯德模型制定了一种改进的标准基算子（SBO）方法。在单组分情况下，通过考虑必要数量的在位态（不止像之前工作那样仅三个），非零温度预测在定性和定量上都得到增强。通过对临界线附近自洽方程的渐近分析，最终数值计算的性能也得到改善。所得结果与蒙特卡罗、张量网络、量子转子方法及实验数据进行了比较。在双组分情况下，SBO推广性较差，能考虑种内热和量子涨落，但不能考虑种间涨落。讨论了这种情况的深层原因。不过，仍预测了相图的非平凡变形以及由化学势变化主导的一级相变。
英文摘要：
We formulate an improved standard basis operator (SBO) method for the single and two-component Bose-Hubbard model in three dimensions. In the first case, nonzero temperature predictions are qualitatively and quantitatively enhanced by taking into account necessary number of on-site states, not just three as in previous works. Performance of the final numerical calculations is also improved by asymptotic analysis of the self-consistent equations near the critical line. Obtained results are compared with Monte-Carlo, tensor networks, Quantum Rotor Approach and experimental data. In the two-component case, SBO generalizes rather poorly, being able to account for intra-species thermal and quantum fluctuations, but not the inter-species ones. Deeper reasons for this situation are discussed. Still however, non-trivial deformation of the phase diagrams is predicted, together with first-order phase transitions steered by the changes in chemical potential.
