Goutéraux Blaise, Mefford Eric
CPHT, CNRS, École Polytechnique, IP Paris, F-91128 Palaiseau, France.
Phys Rev Lett. 2020 Apr 24;124(16):161604. doi: 10.1103/PhysRevLett.124.161604.
The normal density of a translation-invariant superfluid often vanishes at zero temperature, as is observed in superfluid Helium and conventional superconductors described by BCS theory. Here we show that this need not be the case. We investigate the normal density in models of quantum critical superfluids using gauge-gravity duality. Models with an emergent infrared Lorentz symmetry lead to a vanishing normal density. On the other hand, models which break the isotropy between time and space may enjoy a nonvanishing normal density, depending on the spectrum of irrelevant deformations around the underlying quantum critical ground state. Our results may shed light on recent measurements of the superfluid density and low energy spectral weight in superconducting overdoped cuprates.
平移不变超流体的正常密度在零温度下通常会消失，这在超流氦和由BCS理论描述的传统超导体中都有观察到。在这里我们表明情况并非一定如此。我们使用规范 - 引力对偶性研究量子临界超流体模型中的正常密度。具有涌现红外洛伦兹对称性的模型会导致正常密度消失。另一方面，破坏时间和空间之间各向同性的模型可能具有非零的正常密度，这取决于围绕潜在量子临界基态的无关变形谱。我们的结果可能会为超导过掺杂铜酸盐中超流体密度和低能谱权重的近期测量提供启示。
