arXiv subjects

Makoto Natsuume

Publications and source records attributed to Makoto Natsuume.

At least 19 recordsLinked to original sources

arXiv2026

The dual Ginzburg-Landau theory for a holographic superfluid/superconductor: Critical dynamics

Holographic superfluids/superconductors are one of the most studied systems in the AdS/CFT duality. In the low-energy, in the long-wavelength limit, they should be described by a Ginzburg-Landau theory. For critical dynamics, one expects that they belong to "model F" universality class. We consider a bulk 5-dimensional holographic superfluid/superconductor in the probe limit. For the holographic superconductor, we impose the boundary Maxwell equation to make the boundary Maxwell field dynamical. We identify the dual model F equations where numerical coefficients are obtained exactly.

hep-th↗

arXiv2026

Pole-skipping without master variable and holographic superfluids

The pole-skipping is a universal property of Green's functions at strong coupling found by the AdS/CFT duality. There is a conventional formalism of the pole-skipping, but it relies on the existence of a "master variable." Namely, it is applicable to a system with a single field. We propose an alternative formalism that does not rely on a master variable. As an example, we study the pole-skipping of holographic superfluids. A "hydrodynamic" pole such as the diffusion pole is usually regarded as a pole-skipping point. But we point out that not all hydrodynamic poles are pole-skipping points.

hep-th↗

arXiv2026

Comments on higher-derivative corrections in the AdS/CFT duality

We point out that some works on higher-derivative corrections in the AdS/CFT duality use inappropriate "AdS/CFT dictionary." We illustrate the problem using a class of holographic superconductors in the Gauss-Bonnet black hole background. We also point out another problem in previous works. These modifications can change the qualitative behavior of physical quantities such as the spontaneous condensate. Whether the condensate increases or decreases under higher-derivative corrections depends on the system one considers, and there is no universality in this sense.

hep-th↗

arXiv2026

The dual Ginzburg-Landau theory for a holographic superconductor: Finite coupling corrections

The holographic superconductor is the holographic dual of superconductors. We recently identified the dual Ginzburg-Landau (GL) theory for a class of bulk 5-dimensional holographic superconductors (arXiv:2207.07182 [hep-th]). However, the result is the strong coupling limit or the large-$N_c$ limit. A natural question is how the dual GL theory changes at finite coupling. We identify the dual GL theory for a minimal holographic superconductor at finite coupling (Gauss-Bonnet holographic superconductor), where numerical coefficients are obtained exactly. The GL parameter $κ$ increases at finite coupling, namely the system approaches a more Type-II superconductor like material. We also point out two potential problems in previous works: (1) the "naive" AdS/CFT dictionary, and (2) the condensate determined only from the GL potential terms. As a result, the condensate increases at finite coupling unlike common folklore.

hep-th↗

arXiv2025

What is the dual Ginzburg-Landau theory for holographic superconductors?

Holographic superconductors are holographic duals of superconductors. Macroscopically, a superconductor should be described by the Ginzburg-Landau (GL) theory. There is ample evidence that the holographic superconductors are described by the standard GL theory, but the exact form of the dual GL theory is little known. We identify the dual GL theory for a class of bulk 5-dimensional holographic superconductors, where numerical coefficients are obtained exactly.

hep-th↗

arXiv2023

Pole-skipping as missing states

It remains unclear in general how the pole-skipping appears as a physical phenomenon, and we study the issue in the context of the AdS soliton. The pole-skipping has been discussed in black hole backgrounds, but the pole-skipping occurs even in the AdS soliton background. The geometry has a compact $S^1$-direction, and we compute the mass spectrum for the bulk scalar field, the bulk Maxwell field, and the gravitational perturbations with $S^1$ momentum. We show that the pole-skipping leaves its fingerprint in the the normal mode spectrum. The spectrum has some puzzling features because the would-be states are missing at pole-skipping points. The puzzling features disappear once one takes into account these pole-skipping points that we call "missing states."

hep-th↗

arXiv2023

Pole-skipping in a non-black-hole geometry

The pole-skipping has been discussed in black hole backgrounds, but we point out that the pole-skipping exists even in a non-black-hole background, the AdS soliton. For black holes, the pole-skipping points are typically located at imaginary Matsubara frequencies $ω=-(2πT)ni$ with an integer $n$. The AdS soliton is obtained by the double Wick rotation from a black hole. As a result, the pole-skipping points are located at $q_z=-(2πn)/l$, where $l$ is the $S^1$ periodicity and $q_z$ is the $S^1$ momentum. The ``chaotic" and the ``hydrodynamic" pole-skipping points lie in the physical region. We also propose a method to identify all pole-skipping points instead of the conventional method.

hep-th↗

arXiv2022

Holographic Meissner Effect

The holographic superconductor is the holographic dual of superconductivity, but there is no Meissner effect in the standard holographic superconductor. This is because the boundary Maxwell field is added as an external source and is not dynamical. We show the Meissner effect analytically by imposing the semiclassical Maxwell equation on the AdS boundary. Unlike in the Ginzburg-Landau (GL) theory, the extreme Type I limit cannot be reached even in the $e\to\infty$ limit where $e$ is the $U(1)$ coupling of the boundary Maxwell field. This is due to the bound current which is present even in the pure bulk Maxwell theory. In the bulk 5-dimensional case, the GL parameter and the dual GL theory are obtained analytically for the order parameter of scaling dimension 2.

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arXiv2021

Nonuniqueness of scattering amplitudes at special points

We point out little discussed phenomenon in elementary quantum mechanics. In one-dimensional potential scattering problems, the scattering amplitudes are not uniquely determined at special points in parameter space. We examine a few explicit examples. We also discuss the relation with the pole-skipping phenomena recently found in holographic duality. In the holographic pole-skipping, the retarded Green's functions are not uniquely determined at imaginary Matsubara frequencies. It turns out that this universality comes from the fact that the corresponding potential scattering problem has the angular momentum potential.

quant-ph↗

arXiv2021

Pole-skipping and zero temperature

We study the pole-skipping phenomenon of the scalar retarded Green's function in the rotating BTZ black hole background. In the static case, the pole-skipping points are typically located at negative imaginary Matsubara frequencies $ω=-(2πT)ni$ with appropriate values of complex wave number $q$. But, in a $(1+1)$-dimensional CFT, one can introduce temperatures for left-moving and right-moving sectors independently. As a result, the pole-skipping points $ω$ depend both on left and right temperatures in the rotating background. In the extreme limit, the pole-skipping does not occur in general. But in a special case, the pole-skipping does occur even in the extreme limit, and the pole-skipping points are given by right Matsubara frequencies.

hep-th↗

arXiv2020

Nonuniqueness of Green's functions at special points

We investigate a new property of retarded Green's functions using AdS/CFT. The Green's functions are not unique at special points in complex momentum space. This arises because there is no unique incoming mode at the horizon and is similar to the "pole-skipping" phenomenon in holographic chaos. Our examples include the bulk scalar field, the bulk Maxwell vector and scalar modes, and the shear mode of gravitational perturbations. In these examples, the special points are always located at $ω_\star = -i(2πT)$ with appropriate values of complex wave number.

hep-th↗

arXiv2020

Holographic chaos, pole-skipping, and regularity

We investigate the "pole-skipping" phenomenon in holographic chaos. According to the pole-skipping, the energy-density Green's function is not unique at a special point in complex momentum plane. This arises because the bulk field equation has two regular near-horizon solutions at the special point. We study the regularity of two solutions more carefully using curvature invariants. In the upper-half $ω$-plane, one solution, which is normally interpreted as the outgoing mode, is in general singular at the future horizon and produces a curvature singularity. However, at the special point, both solutions are indeed regular. Moreover, the incoming mode cannot be uniquely defined at the special point due to these solutions.

hep-th↗

arXiv2020

Pole-skipping with finite-coupling corrections

Recently, it is shown that many Green's functions are not unique at special points in complex momentum space using AdS/CFT. This phenomenon is similar to the pole-skipping in holographic chaos, and the special points are typically located at $ω_n = -(2πT)ni$ with appropriate values of complex wave number $q_n$. We study finite-coupling corrections to special points. As examples, we consider four-derivative corrections to gravitational perturbations and four-dimensional Maxwell perturbations. While $ω_n$ is uncorrected, $q_n$ is corrected at finite coupling. Some special points disappear at particular values of higher-derivative couplings. Special point locations of the Maxwell scalar and vector modes are related to each other by the electromagnetic duality.

hep-th↗

arXiv2018

Holographic Lifshitz superconductors: Analytic solution

We construct an analytic solution for a one-parameter family of holographic superconductors in asymptotically Lifshitz spacetimes. We utilize this solution to explore various properties of the systems such as (1) the superfluid phase background and the grand canonical potential, (2) the order parameter response function or the susceptibility, (3) the London equation, (4) the background with a superfluid flow or a magnetic field. From these results, we identify the dual Ginzburg-Landau theory including numerical coefficients. Also, the dynamic critical exponent $z_d$ associated with the critical point is given by $z_d=2$ irrespective of the value of the Lifshitz exponent $z$.

hep-th↗

arXiv2017

Kibble-Zurek scaling in holography

The Kibble-Zurek (KZ) mechanism describes the generations of topological defects when a system undergoes a second-order phase transition via quenches. We study the holographic KZ scaling using holographic superconductors. The scaling can be understood analytically from a scaling analysis of the bulk action. The argument is reminiscent of the scaling analysis of the mean-field theory but is more subtle and is not entirely obvious. This is because the scaling is not the one of the original bulk theory but is an emergent one that appears only at the critical point. The analysis is also useful to determine the dynamic critical exponent $z$.

hep-th↗

arXiv2016

AdS/CFT Duality User Guide

This is the draft/updated version of a textbook on "real-world" applications of the AdS/CFT duality for beginning graduate students in particle physics and for researchers in the other fields. The aim of this book is to provide background materials such as string theory, general relativity, nuclear physics, nonequilibrium physics, and condensed-matter physics as well as some key applications of the AdS/CFT duality in a single textbook. Contents: (1) Introduction, (2) General relativity and black holes, (3) Black holes and thermodynamics, (4) Strong interaction and gauge theories, (5) The road to AdS/CFT, (6) The AdS spacetime, (7) AdS/CFT - equilibrium, (8) AdS/CFT - adding probes, (9) Basics of nonequilibrium physics, (10) AdS/CFT - nonequilibrium, (11) Other AdS spacetimes, (12) Applications to quark-gluon plasma, (13) Basics of phase transition, (14) AdS/CFT - phase transition, (15) Exercises.

hep-th↗

arXiv2013

The enhanced holographic superconductor: is it possible?

It is known that time-dependent perturbations can enhance superconductivity and increase the critical temperature. If this phenomenon happens to high-T_c superconductors, one could obtain room-temperature superconductors, but this is still an open issue experimentally. Meanwhile, we would like to understand this phenomenon from gravity dual and see if the enhancement is possible for holographic superconductors. Previous work (arXiv:1104.4098 [hep-th]) has studied this issue by adding a "time-dependent chemical potential," but their analysis is questionable as a true dynamic equilibrium. In particular, the AdS boundary does not supply energy to the bulk spacetime in their setup. A more appropriate way to discuss the enhancement is to add a time-dependent vector potential, i.e., a time-dependent electric field. However, the enhancement does not occur for holographic superconductors.

hep-th↗

arXiv2013

The Incompressible Rindler fluid versus the Schwarzschild-AdS fluid

We study the proposal by Bredberg et al. (1006.1902), where the fluid is defined by the Brown-York tensor on a timelike surface at r=r_c in black hole backgrounds. We consider both Rindler space and the Schwarzschild-AdS (SAdS) black hole. The former describes an incompressible fluid, whereas the latter describes the vanishing bulk viscosity at arbitrary r_c, but these two results do not contradict with each other. We also find an interesting "coincidence" with the black hole membrane paradigm which gives a negative bulk viscosity. In order to show these results, we rewrite the hydrodynamic stress tensor via metric perturbations using the conservation equation. The resulting expressions are suitable to compare with the Brown-York tensor.

hep-th↗