5,482 research outputs found
Holographic Butterfly Effect at Quantum Critical Points
When the Lyapunov exponent in a quantum chaotic system saturates
the bound , it is proposed that this system has a
holographic dual described by a gravity theory. In particular, the butterfly
effect as a prominent phenomenon of chaos can ubiquitously exist in a black
hole system characterized by a shockwave solution near the horizon. In this
paper we propose that the butterfly velocity can be used to diagnose quantum
phase transition (QPT) in holographic theories. We provide evidences for this
proposal with an anisotropic holographic model exhibiting metal-insulator
transitions (MIT), in which the derivatives of the butterfly velocity with
respect to system parameters characterizes quantum critical points (QCP) with
local extremes in zero temperature limit. We also point out that this proposal
can be tested by experiments in the light of recent progress on the measurement
of out-of-time-order correlation function (OTOC).Comment: 7 figures, 15 page
Holographic Metal-Insulator Transition in Higher Derivative Gravity
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
, 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).Comment: 20 pages, 4 figures; typo corrected, added 3 references; minor
revisio
Note on graph-based BCJ relation for Berends-Giele currents
Graph-based Bern-Carasso-Johansson (BCJ) relation for Berends-Giele currents
in bi-adjoint scalar (BS) theory, which is characterized by connected tree
graphs, was proposed in an earlier work. In this note, we provide a systematic
study of this relation. We first prove the relations based on two special types
of graphs: simple chains and star graphs. The general graph-based BCJ relation
established by an arbitrary tree graph is further proved, through Berends-Giele
recursion. When combined with proper off-shell extended numerators, this
relation induces the graph-based BCJ relation for Berends-Giele currents in
Yang-Mills theory. The corresponding relations for amplitudes are obtained via
on-shell limits.Comment: 26 pages, 10 figure
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