论文标题
超氟的热力学起源
Thermodynamic origin of the Landau instability of superfluids
论文作者
论文摘要
在这项工作中，我们重新审视了物质超流体阶段的线性稳定性问题。著名的是，Landau预测，对于足够大的超级流体速度，超流体氦气将变得不稳定。我们证明，这种不稳定性只是从热力学参数中遵循的，它表明它的发作对应于自由能的第二个衍生物基质的特征值之一的符号的变化。在提升下，打开耗散且没有对不变性的任何特定假设，我们表明也会发展线性动力学不稳定性，从而导致平衡周围扰动时间的指数增长。我们的标准专门研究伽利亚超级流体并假设存在准颗粒，与Landau的临界速度相匹配。我们还验证了它是否正确地再现了使用仪表/重力双重性构建的相对论超流体中不稳定性的开始。我们的工作为超流体的兰道不稳定性提供了简单，全面和统一的描述，独立于系统的微观细节。
In this work, we revisit the question of the linear stability of superfluid phases of matter. Famously, Landau predicted superfluid Helium would become unstable for large enough superfluid velocities. We demonstrate that this instability simply follows from a thermodynamic argument, by showing that its onset corresponds to a change of sign of one of the eigenvalues of the matrix of second derivatives of the free energy. Turning on dissipation and without any particular assumption on invariance under boosts, we show that a linear dynamical instability also develops, leading to exponential growth in time of perturbations around equilibrium. Specializing to Galilean superfluids and assuming the existence of quasiparticles, our criterion matches Landau's critical velocity. We also verify that it correctly reproduces the onset of the instability in relativistic superfluids constructed using gauge/gravity duality. Our work provides a simple, comprehensive and unified description of the Landau instability for superfluids independently of the microscopic details of the system.
