Even when ideal solids are insulating, their states with crystallographic defects may have superfluid properties. It became clear recently that edge dislocations in 4He featuring a combination of microscopic quantum roughness and superfluidity of their cores may represent a new paradigmatic class of quasi-one-dimensional superfluids. The new state of matter, termed transverse quantum fluid (TQF), is found in a variety of physical setups. The key ingredient defining the class of TQF systems is infinite compressibility, which is responsible for all other unusual properties such as the quadratic spectrum of normal modes (or even the absence of sharp quasiparticles), irrelevance of the Landau criterion, off-diagonal long-range order at T = 0, and the exponential dependence of the phase slip probability on the inverse flow velocity. From a conceptual point of view, the TQF state is a striking demonstration of the conditional character of many dogmas associated with superfluidity, including the necessity of elementary excitations, in general, and the ones obeying Landau criterion in particular.

中文翻译：

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横向量子超流体


即使理想的固体是绝缘的，它们具有晶体学缺陷的状态也可能具有超流体特性。最近很明显，4He 中的边缘位错结合了微观量子粗糙度和其核心的超流体，可能代表了一类新的准一维超流体范式。新的物质状态称为横向量子流体 （TQF），存在于各种物理设置中。定义 TQF 系统类别的关键因素是无限可压缩性，它负责所有其他不寻常的特性，例如正则模态的二次谱（甚至没有尖锐的准粒子）、朗道准则的不相关性、T = 0 时的非对角线长程阶数以及相滑概率对逆流速的指数依赖性。从概念的角度来看，TQF 状态是许多与超流体相关的教条的条件特征的惊人证明，包括一般基本激励的必要性，特别是那些遵守 Landau 准则的激励。