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arXiv 2407.01072cond-mat.quant-gas
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二维超固体的激发

Excitations of a two-dimensional supersolid

Elena Poli, Danny Baillie, Francesca Ferlaino, P. Blair Blakie

AI总结:

本研究理论探究了含偶极或软核相互作用的二维玻色-爱因斯坦凝聚体超固态的三支无隙激发分支,通过数值计算验证了流体动力学理论对声速的描述,并明确两类超固体的不同极限特征。

摘要:

我们对具有偶极-偶极相互作用或软核相互作用的玻色-爱因斯坦凝聚体二维超固态的激发开展了理论研究。该超固态存在三支无隙激发分支,源于自发破缺的连续对称性。其中两支与纵声波相关,与一维超固体中的情况类似;第三支为横波,由二维晶体的非零剪切模量产生。我们给出了激发以及表征密度涨落的动态结构因子的数值计算结果,并研究了它们在超流体到超固体的不连续相变过程中的行为。研究表明,声速可由纳入了包含剪切模量在内的广义弹性参数的流体动力学理论描述。此外,我们证实偶极超固体和软核超固体表现出不同特征,分别处于体不可压缩极限和刚性晶格极限。

英文摘要:

We present a theoretical study of the excitations of the two-dimensional supersolid state of a Bose-Einstein condensate with either dipole-dipole interactions or soft-core interactions. This supersolid state has three gapless excitation branches arising from the spontaneously broken continuous symmetries. Two of these branches are related to longitudinal sound waves, similar to those in one-dimensional supersolids. The third branch is a transverse wave arising from the non-zero shear modulus of the two-dimensional crystal. We present the results of numerical calculations for the excitations and dynamic structure factor characterising the density fluctuations, and study their behavior across the discontinuous superfluid to supersolid transition. We show that the speeds of sound are described by a hydrodynamic theory that incorporates generalized elastic parameters, including the shear modulus. Furthermore, we establish that dipolar and soft-core supersolids manifest distinct characteristics, falling into the bulk incompressible and rigid lattice limits, respectively.

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