标题： 从自发对称性破缺到显式对称性破缺在有限系统中的表现：杂质的玻色束缚态 显示英文标题

标题： From spontaneous to explicit symmetry breaking in a finite-sized system: Bosonic bound states of an impurity

摘要： 在超冷排斥玻色系统中存在单一吸引杂质时，可以驱动从均匀态到局域态的转变，如我们在此对一维环形系统所展示的那样。 在少体极限下，玻色子在杂质周围的局域化，如成对相关性所见，伴随着低能模式，这些模式类似于希格斯-安德森和诺姆-戈尔德斯通类似模式的有限尺寸前驱体。 调节杂质-玻色子质量比允许探索哈密顿量连续旋转对称性的自发破缺到显式破缺的转变。 我们将类似希格斯-安德森模式的最小值作为少体极限中局域化开始的标志，与结合的平均场预测进行比较。 我们发现随着玻色子-玻色子排斥力的增加，少体精确对角化结果与结合的平均场预测之间的吻合度有所提高。 显示英文摘要

摘要： The presence of a single attractive impurity in an ultracold repulsive bosonic system can drive a transition from a homogeneous to a localized state, as we here show for a one-dimensional ring system. In the few-body limit the localization of the bosons around the impurity, as seen in the pair correlations, is accompanied by low-lying modes that resemble finite-size precursors of Higgs-Anderson and Nambu-Goldstone-like modes. Tuning the impurity-boson mass ratio allows for the exploration of the transition from a spontaneous to an explicit breaking of the continuous rotational symmetry of the Hamiltonian. We compare the minimum of the Higgs-Anderson-like mode as a marker of the onset of localization in the few-body limit to mean-field predictions of binding. We find improved agreement between the few-body exact diagonalization results and mean-field predictions of binding with increasing boson-boson repulsion.