All Results

Note on the butterfly effect in holographic superconductor models

Yi Ling; Peng Liu; Jian-Pin WuSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

In this note we remark that the butterfly effect can be used to diagnose the phase transition of superconductivity in a holographic framework. Speci cally, we compute the butterfly velocity in a charged black hole background as well as anisotropic backgrounds with Q-lattice structure. In both cases we nd its derivative to the temperature is discontinuous at critical points. We also ropose that the butterfly velocity can signalize the occurrence of thermal phase transition in general holographic models. |

Holographic incoherent transport in Einstein-Maxwell-Dilaton Gravity

Zhenhua Zhou; Yi Ling; Jian-Pin WuSubjects: Physics >> Nuclear Physics

Recent progress in holographic approach makes it more transparent that each conductivity can be decomposed into the coherent contribution due to momentum relaxation and the incoherent contribution due to intrinsic current relaxation. In this paper we investigate this decomposition in the framework of Einstein-Maxwell-Dilaton theory. We derive the perturbation equations which are decoupled for a large class of background solutions, and then obtain the analytic results of conductivity with slow momentum relaxation in low frequency approximation, which is consistent with the known results from memory matrix techniques. |

A novel insulator by holographic Q-lattices

Yi Ling; Peng Liu; Jian-Pin WuSubjects: Physics >> Nuclear Physics

We construct a bulk geometry with Q-lattice structure, which is implemented by two gauge fields and a coupling between the lattice and the Maxwell field. This gravity dual model can describe a novel insulator which exhibits some key features analogous to Mott insulator. In particular, a hard gap in insulating phase as well as vanishing DC conductivity can be simultaneously achieved. In addition, we discuss the non-Drude behavior of the optical conductivity in low frequency region in insulating phase, which exhibits some novel characteristics different from ordinary Mott insulator. |

Building a doped Mott system by holography

Yi Ling; Peng Liu; Chao Niu; Jian-Pin Wu; Zhuo-Yu XianSubjects: Physics >> Nuclear Physics

We construct a holographic model in the framework of Q-lattices whose dual exhibits metal-insulator transitions. By introducing an interacting term between the Q-lattice and the electromagnetic field in bulk geometry, we find such kind of transition can be Mott-like. The evidences are presented as follows. i) The transition from a metallic phase to an insulating phase occurs when the lattice constant becomes larger. ii) A hard gap in the insulating phase can be manifestly observed in the optical conductivity. Nevertheless, in the zero temperature limit this model exhibits novel metallic behavior, featured by a gap as well as a zero-frequency mode with tiny spectral weight. It implies that our model is dual to a doped Mott system in one dimension where umklapp scattering is frozen at zero temperature. The similarity between this model and some organic linear chain conductors is briefly discussed. |

DC and Hall conductivity in holographic massive Einstein-Maxwell-Dilaton gravity

Zhenhua Zhou; Jian-Pin Wu; Yi LingSubjects: Physics >> Nuclear Physics

We investigate the holographic DC and Hall conductivity in massive Einstein-Maxwell-Dilaton (EMD) gravity. Two special EMD backgrounds are considered explicitly. One is dyonic Reissner-Nordstro╩-AdS (RN-AdS) geometry and the other one is hyperscaling violation AdS (HV-AdS) geometry. We find that the linear-T resistivity and quadratic-T inverse Hall angle can be simultaneously achieved in HV-AdS models, providing a hint to construct holographic models confronting with the experimental data of strange metal in future. |

Holographic Entanglement Entropy Close to Quantum Phase Transitions

Yi Ling; Peng Liu; Chao Niu; Jian-Pin Wu; Zhuo-Yu XianSubjects: Physics >> Nuclear Physics

We investigate the holographic entanglement entropy (HEE) of a strip geometry in four dimensional Q-lattice backgrounds, which exhibit metal-insulator transitions in the dual field theory. Remarkably, we find that the HEE always displays a peak in the vicinity of the quantum critical points. Our model provides the first direct evidence that the HEE can be used to characterize the quantum phase transition (QPT). We also conjecture that the maximization behavior of HEE at quantum critical points would be universal in general holographic models. |

Holographic Metal-Insulator Transition in Higher Derivative Gravity

Yi Ling; Peng Liu; Jian-Pin Wu; Zhenhua ZhouSubjects: Physics >> Nuclear Physics

We introduce a Weyl term into the Einstein-Maxwell-Axion theory in four dimensional spacetime. Up to the first order of the Weyl coupling parameter?γ, we construct charged black brane solutions without translational invariance in a perturbative manner. Among all the holographic frameworks involving higher derivative gravity, we are the first to obtain metal-insulator transitions (MIT) when varying the system parameters at zero temperature. Furthermore, we study the holographic entanglement entropy (HEE) of strip geometry in this model and find that the second order derivative of HEE with respect to the axion parameter exhibits maximization behavior near quantum critical points (QCPs) of MIT. It testifies the conjecture in?1502.03661?and?1604.04857?that HEE itself or its derivatives can be used to diagnose quantum phase transition (QPT). |

Characterization of Quantum Phase Transition using Holographic Entanglement Entropy

Yi Ling; Peng Liu; Jian-Pin WuSubjects: Physics >> Nuclear Physics

The entanglement exhibits extremal or singular behavior near quantum critical points (QCPs) in many condensed matter models. These intriguing phenomena, however, still call for a widely accepted understanding. In this letter we study this issue in holographic framework. We investigate the connection between the holographic entanglement entropy (HEE) and the quantum phase transition (QPT) in a lattice-deformed Einstein-Maxwell-Dilaton theory. Novel backgrounds exhibiting metal-insulator transitions (MIT) have been constructed in which both metallic phase and insulating phase have vanishing entropy density in zero temperature limit. We find that the first order derivative of HEE with respect to lattice parameters exhibits extremal behavior near QCPs. We propose that it would be a universal feature that HEE or its derivatives with respect to system parameters can characterize QPT in a generic holographic system. Our work opens a window for understanding the relation between entanglement and the QPT from holographic perspective. |

[1 Pages/ 8 Totals]