14507542
Fractional quantum Hall effect via holography: Chern-Simons, edge states and hierarchy
We present three holographic constructions of fractional quantum Hall effect (FQHE) via string theory. The first model studies edge states in FQHE using supersymmetric domain walls in = 6 Chern-Simons theory. We show that D4-branes wrapped on 1 or D8-branes wrapped on 3 create edge states that shift the rank or the level of the gauge group, respectively. These holographic edge states correctly reproduce the Hall conductivity. The second model presents a holographic dual to the pure U(N)k (Yang-Mills-)Chern-Simons theory based on a D3-D7 system. Its holography is equivalent to the level-rank duality, which enables us to compute the Hall conductivity and the topological entanglement entropy. The third model introduces the first string theory embedding of hierarchical FQHEs, using IIA string on 2/Zn.
6352305
ABJM with Flavors and FQHE
We add fundamental matters to the = 6 Chern-Simons theory (ABJM theory), and show that D6-branes wrapped over AdS4 × S3/2 in type IIA superstring theory on AdS4 × 3 give its dual description with = 3 supersymmetry. We confirm this by the arguments based on R-symmetry, supersymmetry, and brane configuration of ABJM theory. We also analyze the fluctuations of the D6-brane and compute the conformal dimensions of dual operators. In the presence of fractional branes, the ABJM theory can model the fractional quantum Hall effect (FQHE), with RR-fields regarded as the external electric-magnetic field. We show that an addition of the flavor D6-brane describes a class of fractional quantum Hall plateau transitions.
119529056
Supersymmetric Probes in a Rotating 5D Attractor
Abstract Supersymmetric zero-brane and one-brane probes in the squashed AdS 2 × S 3 near-horizon geometry of the BMPV black hole are studied. Supersymmetric zero-brane probes stabilized by orbital angular momentum on the S 3 are found and shown to saturate a BPS bound. We also find supersymmetric one-brane probes which have momentum and winding around a U ( 1 ) L × U ( 1 ) R torus in the S 3 and in some cases are static.
14536751
Some No-go Theorems for String Duals of Non-relativistic Lifshitz-like Theories
We study possibilities of string theory embeddings of the gravity duals for non-relativistic Lifshitz-like theories with anisotropic scale invariance. We search classical solutions in type IIA and eleven-dimensional supergravities which are expected to be dual to (2+1)-dimensional Lifshitz-like theories. Under reasonable ansatze, we prove that such gravity duals in the supergravities are not possible. We also discuss a possible physical reason behind this.
53121461
Quantum decoherence with holography
A bstractQuantum decoherence is the loss of a system’s purity due to its interaction with the surrounding environment. Via the AdS/CFT correspondence, we study how a system decoheres when its environment is a strongly-coupled theory. In the FeynmanVernon formalism, we compute the influence functional holographically by relating it to the generating function of Schwinger-Keldysh propagators and thereby obtain the dynamics of the system’s density matrix.We present two exactly solvable examples: (1) a straight string in a BTZ black hole and (2) a scalar probe in AdS5. We prepare an initial state that mimics Schrödinger’s cat and identify different stages of its decoherence process using the time-scaling behaviors of Rényi entropy. We also relate decoherence to local quantum quenches, and by comparing the time evolution behaviors of the Wigner function and Rényi entropy we demonstrate that the relaxation of local quantum excitations leads to the collapse of its wave-function.
16051323
Comment on `Cosmological Topological Massive Gravitons and Photons'
In a recent paper (arXiv: 0801.4566) it was shown that all global energy eigenstates of asymptotically $AdS_3$ chiral gravity have non-negative energy at the linearized level. This result was questioned (arXiv: 0803.3998) by Carlip, Deser, Waldron and Wise (CDWW), who work on the Poincare patch. They exhibit a linearized solution of chiral gravity and claim that it has negative energy and is smooth at the boundary. We show that the solution of CDWW is smooth only on that part of the boundary of $AdS_3$ included in the Poincare patch. Extended to global $AdS_3$, it is divergent at the boundary point not included in the Poincare patch. Hence it is consistent with the results of (arXiv: 0801.4566).
118572221
Analytic modeling of instabilities driven by higher-order modes in HLS II RF system with a higher-harmonic cavity
The utility of a passive fourth-harmonic cavity plays key role in suppressing longitudinal beam instabilities in the electron storage ring and lengthens the bunch by a factor of 2.6 for the phase II project of Hefei Light Source(HLS II). Meanwhile, instabilities driven by higher-order modes(HOM) may limit the performance of the higher-harmonic cavity. In this paper, the parasitic coupled-bunch instability which is driven by narrow band parasitic modes and the microwave instability which is driven by broadband HOM are both modeled analytically. The analytic modeling results are in good agreement with that of our previous simulation study and indicate that the passive fourth-harmonic cavity suppresses parasitic coupled-bunch instabilities and the microwave instability. The modeling suggests that a fourth-harmonic cavity may be successfully used at HLS II.
18978953
Holographic RG flow and the quantum effective action
The calculation of the full (renormalized) holographic action is undertaken in general Einstein-scalar theories. The appropriate formalism is developed and the renormalized effective action is calculated up to two derivatives in the metric and scalar operators. The holographic RG equations involve a generalized Ricci flow for the space-time metric as well as the standard β-function flow for scalar operators. Several examples are analyzed and the effective action is calculated. A set of conserved quantities of the holographic flow is found, whose interpretation is not yet understood.
36928210
The nonlinear effects of fringe fields in HLS
The main body of HLS (Hefei Light Source) is an 800 MeV electron storage ring, whose circumference is about 66 m. As a typical small ring, although the sextupole fields for correction of chromaticities are relatively weak, there still exist strong nonlinear fields coming from fringe fields of dipole and quadrupole magnets. In this paper, the effects of fringe fields on chromaticities and tune shifts with amplitude were discussed and calculated for HLS storage ring. Under the low injection energy, the tune shifts with amplitude coming from fringe fields are one of important sources of transverse Landau damping, which is main stabilizing mechanism for HLS ring.
118344568
Holographic p-wave superconductors in quasi-topological gravity
We construct a holographic p-wave superconductor model in the framework of quasi-topological gravity in the probe limit. The relation between the critical temperature and the coupling parameters of higher curvature terms is investigated. The numerical results for conductivity are presented as well. It turns out that our data fit the Drude model very well in the low-frequency limit, and the values of dc conductivity as well as the relaxation time are obtained numerically.
73568718
The Upgrade of the Hefei Light Source HLS Transport Line
To enhance the performance of Hefei Light Source, an upgrade project is undergoing. The magnet lattice of storage ring will be reconstructed with 4 DBA cells, whose advantages are lower beam emittance and more straight section available for insertion devices. In order to assure smooth beam accumulation process under new low emittance lattice, the injector, which is composed of electron linac and beam transfer line, would be updated. The detail upgrading of Hefei Light Source transport line will be described in this paper. It include the upgrading of lattice, the orbit control of beam transfer line and others. It is hopeful to realize a high transfer efficiency and high injection efficiency for new low beam emittance storage ring. INTRODUCTION HLS is a dedicated second generation VUV light source, whose main body is composed of 800MeV electron storage ring, 200MeV linac and beam transfer line. There are two factors affecting light source performance: large beam emittance and less number of straight sections. In order to improve HLS performance, an upgrading is undergoing now[1]. The main purpose of upgrading are increasing the number of insertion devices, lowering the ring’s beam emittance and improving the beam orbit stability. After upgrading, separate function DBA was adopted as the standard cell of ring. There are four 4.0m long straight section and four 2.3m long straight section. The emittance of lattice will be reduced to 36nm.rad in achromatic mode and to 20nm.rad in distributed dispersion mode. The orbit stability will be smaller than 5μm. After upgrading, the beam accumulation process will be more difficult under low injection energy. Improving injection efficiency is essential to obtain high beam intensity. In order to improve injection efficiency, the injector should be upgraded also. The demanding to the injection beam is shown in table 1. As comparing, the old injector beam properties are shown in table 1 also. The injector of HLS was constructed twenty years ago, and poor beam properties cannot meet the requirements of new ring. Several upgrades were proposed. A new thermal-cathode gun will be constructed to reduce the beam emittance and to get ns pulse time structure. Cooperating with new time system, bunch by bunch filling would be realized in the future. A new phase control system also will adapt to promote the energy stability of injector. An new beam trajectory monitoring system and related steering magnet system will be applied. It will be helpful to control the position and angle of injected beam. Table 1: Demanding to the Injection Beam parameters demanding Old machine Charge 1nc/1ns 80mA&0.5μs Energy spread 0.5% 0.8% Energy stibility 0.5% 0.7% Normalized emittance (rms) 40mm•mrad 200mm•mrad