广义测不准关系与三维BTZ黑洞熵

通过应用在量子引力中,由广义测不准关系得出的新的态密度方程,研究三维BTZ背景下黑洞的熵.当取广义测不准关系中引入的,具有Planck量级与空间维数有关的常数λ为特定值时,得到BTZ黑洞Bekenstein-Hawking 熵和修正项.由于利用新的态密度方程,在计算中不存在用brick-wall模型计算黑洞熵时出现的发散项和小质量近似.所得结论,从量子统计力学角度给出了黑洞Bekenstein-Hawking 熵的修正值,使人们对黑洞熵的修正值有更深入的认识. 关键词： 广义测不准关系 量子统计 BTZ黑洞熵     

Holographic superconductor developed in BTZ black hole background with backreactions

We develop a holographic superconductor in BTZ black hole background with backreactions. We investigate the influence of the backreaction on the condensation of the scalar hair and the dynamics of perturbation in the background spacetime. When the Breitenlohner-Freedman bound is approached, we argue that only one of two possible operators can reflect the real property of the condensation in the holographic superconductor. This argument is supported by the investigation in dynamics.     

Conformal field theory on the horizon of a BTZ black hole

In a three-dimensional spacetime with negative cosmological constant, general relativity can be written as two copies of SO(2,1) Chern-Simons theory. On a manifold with a boundary, the Chern-Simons theory induces a conformal field theory—Wess-Zumino-Witten theory on the boundary. In this paper, it is shown that with suitable boundary conditions for a Banados-Teitelboim-Zanelli black hole, the Wess-Zumino-Witten theory can reduce to a chiral massless scalar field on the horizon.     

Cosmic string in the BTZ black hole background with time-dependent tension

In this Letter, we study the equation of circular loops with time-dependent tension in the BTZ black hole background. We obtain various cases where cosmic string loops finally collapse to form black holes. Also, we study effect of the BTZ black hole mass and angular momentum on the evolution of cosmic string loops. We find the critical values of initial radii as a limit for the cosmic string loops collapsing to form black holes.     

Quasinormal modes of BTZ black hole and Hawking‐like radiation in graphene

The Bañados‐Teitelboim‐Zanelli (BTZ) black hole model corresponds to a solution of (2+1)‐dimensional Einstein gravity with negative cosmological constant, and by a conformal rescaling its metric can be mapped onto the hyperbolic pseudosphere surface (Beltrami trumpet) with negative curvature. Beltrami trumpet shaped graphene sheets have been predicted to emit Hawking radiation that is experimentally detectable by a scanning tunnelling microscope. Here, for the first time we present an analytical algorithm that allows variational solutions to the Dirac Hamiltonian of graphene pseudoparticles in BTZ black hole gravitational field by using an approach based on the formalism of pseudo‐Hermitian Hamiltonians within a discrete‐basis‐set method. We show that our model not only reproduces the exact results for the real part of quasinormal mode frequencies of (2+1)‐dimensional spinless BTZ black hole, but also provides analytical results for the real part of quasinormal modes of spinning BTZ black hole, and also offers some predictions for the observable effects with a view to gravity‐like phenomena in a curved graphene sheet.

     

Hawking radiation from the charged and magnetized BTZ black hole via covariant anomaly

This paper discusses Hawking radiation from the charged and magnetized Ba?ados--Teitelboim--Zanelli (BTZ) black hole from the viewpoint of anomaly, initiated by Robinson and Wilczek recently. It reconstructs the electromagnetic field tensor and the Lagrangian of the field corresponding to the source with electric and magnetic charges to redefine an equivalent charge and gauge potential. It employs the covariant anomaly cancellation method to determine the compensating fluxes of charge flow and energy-momentum tensor, which are shown to match with those of the 2-dimensional blackbody radiation at the Hawking temperature exactly.     

Two-charged non-extremal rotating black holes in seven-dimensional gauged supergravity: The single-rotation case

We construct the solution for non-extremal charged rotating black holes in seven-dimensional gauged supergravity, in the case with only one rotation parameter and two independent charges. Using the Boyer-Lindquist coordinates, the metric is expressed in a generalized form of the ansatz previously presented in [S.Q. Wu, Phys. Rev. D 83 (2011) 121502(R)], which may be helpful to find the most general non-extremal two-charged rotating black hole with three unequal rotation parameters. The conserved charges for thermodynamics are also computed.     

Fermionic wigs for BTZ black holes

We compute the wig for the BTZ black hole, namely the complete non-linear solution of supergravity equations with all fermionic zero modes. We use a “gauge completion” method starting from _AdS3${\mathit{AdS}}_3$ Killing spinors to generate the gravitinos fields associated to the BH and we compute the back-reaction on the metric. Due to the anticommutative properties of the fermionic hairs the resummation of these effects truncates at some order. We illustrate the technique proposed in a precedent paper in a very explicit and analytical form. We also compute the mass, the angular momentum and other charges with their corrections.     

Stealth scalar field overflying a 2+1 black hole

A nontrivial scalar field configuration of vanishing energy-momentum is reported. These matter configurations have no influence on the metric and therefore they are not be “detected" gravitationally. This phenomenon occurs for a time–dependent nonminimally coupled and self-interacting scalar field on the 2+1 (BTZ) black hole geometry. We conclude that such stealth configurations exist for the static 2+1 black hole for any value of the nonminimal coupling parameter ζ≠0 with a fixed self-interaction potential U _ζ(Φ). For the range 0 < ζ≤1/2 potentials are bounded from below and for the range 0 < ζ < 1/4 the stealth field falls into the black hole and is swallowed by it at an exponential rate, without any consequence for the black hole.     

Spectroscopy of X2Y4 (D2h) molecules: tensorial formalism adapted to the O(3)⊃D2h chain, Hamiltonian and transition moment operators

A tensorial formalism adapted to the case of the X₂Y₄ molecules with D_2h symmetry has been developed in the same way as in the previous works on XY₄ (T_d) and XY₆ (O_h) spherical tops and XY₅Z (C_4v) symmetric tops. Here, we use the O(3)⊃D_2h group chain. All the coupling coefficients and formulas for the computation of matrix elements are given for this chain and used in the case of the Hamiltonian and transition moment operators.     

Thermodynamics and weak cosmic censorship conjecture of BTZ black holes in extended phase space

As a charged fermion drops into a BTZ black hole, the laws of thermodynamics and the weak cosmic censorship conjecture are investigated in both the normal and extended phase space, where the cosmological parameter and renormalization length are regarded as extensive quantities. In the normal phase space, the first and second law of thermodynamics, and the weak cosmic censorship are found to be valid. In the extended phase space, although the first law and weak cosmic censorship conjecture remain valid, the second law is dependent on the variation of the renormalization energy d K. Moreover, in the extended phase space, the configurations of extremal and near-extremal black holes are not changed, as they are stable, while in the normal phase space, the extremal and near-extremal black holes evolve into non-extremal black holes.     

LETTER: Quantum Creation of BTZ Black Hole

The constrained instanton method is used to study quantum creation of a BTZ black hole. It is found that the relative creation probability is the exponential of the negative sum of the entropy associated with the outer and inner black hole horizons. The quantum creations of the 4- or higher dimensional versions of the BTZ black hole are also studied.     

Luminescent properties of KGd1−x(WO4)2:Eux and KGd1−x(WO4)2−y(MoO4)y:Eux phosphors in UV-VUV regions

KGd_1−x(WO₄)_2−y(MoO₄)_y:Eu³⁺_x(0.1?x?0.75, y=0 and 0.2) phosphors are synthesized through traditional solid-state reaction and their luminescent properties in ultraviolet (UV) and vacuum ultraviolet (VUV) regions are investigated. Under 147 nm excitation, these phosphors show characteristic red emission with good color purity. In order to improve their emission intensity, the MoO₄²⁻ (20 wt%) is introduced into the anion of KGd_1−x(WO₄):Eu³⁺_x. The Mo⁶⁺ and Eu³⁺ co-doped KGd(WO₄)₂ phosphors show higher emission intensity in comparison with the singly Eu³⁺-doped KGd(WO₄)₂ in VUV region. The chromaticity coordination of KGd_0.45(WO₄):Eu³⁺_0.55 is (x=0.669, y=0.331), while that of KGd_0.45(WO₄)_1.8(MoO₄)_0.2:Eu³⁺_0.55 is (x=0.666, y=0.334) in VUV region.     

Stabilization of a very high-k crystalline ZrO2 phase by post deposition annealing of atomic layer deposited ZrO2/La2O3 dielectrics on germanium

The impact of the ZrO₂/La₂O₃ film thickness ratio and the post deposition annealing in the temperature range between 400 °C and 600 °C on the electrical properties of ultrathin ZrO₂/La₂O₃ high-k dielectrics grown by atomic layer deposition on (1 0 0) germanium is investigated. As-deposited stacks have a relative dielectric constant of 24 which is increased to a value of 35 after annealing at 500 °C due to the stabilization of tetragonal/cubic ZrO₂ phases. This effect depends on the absolute thickness of ZrO₂ within the dielectric stack and is limited due to possible interfacial reactions at the oxide/Ge interface. We show that adequate processing leads to very high-k dielectrics with EOT values below 1 nm, leakage current densities in the range of 0.01 A/cm², and interface trap densities in the range of 2-5 × 10¹² eV⁻¹ cm⁻².     

Effect of post-deposition annealing on structural and electrical properties of high-k HoTiO3 gate dielectrics

In this article, the authors developed a high-k HoTiO₃ gate dielectric deposited on Si (1 0 0) through reactive cosputtering. They found that the HoTiO₃ dielectrics annealed at 800 °C exhibited excellent electrical properties such as high capacitance value, small density of interface state, almost no hysteresis voltage, and low leakage current. This phenomenon is attributed to the decrease in intrinsic defect (related to oxygen vacancy) due to a rather well-crystallized HoTiO₃ structure and composition observed by X-ray diffraction, secondary ion mass spectrometry, and X-ray photoelectron spectroscopy, respectively.     

Effects of electron beam current density and temperature on peak height ratios Dj/D0 for cathodoluminescence of Ln2O2S:Eu

The change in the initial and steady state (∼0 and 5 s after initiation of electron beam irradiation) peak heights from the ⁵D₂⇒⁷F₃, ⁵D₁⇒⁷F₃ and ⁵D₀⇒⁷F₂ cathodoluminescent transitions from Eu³⁺ have been studied for Ln₂O₂S:Eu³⁺ (Ln=La, Gd) phosphors. Specifically, the intensity ratio of these transitions, designated as ⁵D₁/⁵D₀, increased and then decreased for both La₂O₂S:Eu³⁺ (0.1 mole%) and Gd₂O₂S:Eu³⁺ (0.4 mole%), as the current density was changed from 10 towards a 1000 μA/cm². These effects were shown to be consistent with feeding from the higher ⁵D₂ excited state to the lower energy ⁵D₁ excited state, resulting in an increase of the ⁵D₁/⁵D₀ ratio at low current densities. At higher current densities, energy was funneled from the ⁵D₁-⁵D₀ states, resulting in a decrease of the ⁵D₁/⁵D₀ ratio. These effects of feeding versus funneling were dependent on both the Eu³⁺ concentration and current density, and changed with time (i.e., approached a steady state after ∼5 s) due to increased activator interactions from induced internal electric fields. The magnitude of thermal quenching versus interaction quenching was investigated using changes of the peak height ratios of ⁵D₂/⁵D₀ and ⁵D₁/⁵D₀.     

Born-Oppenheimer breakdown and non-adiabatic lifetimes of rovibrational levels of D2 lying near the n = 2 dissociation limit: Experiment and theory

The singlet gerade states of the hydrogen molecule are strongly affected by the breakdown of the Born-Oppenheimer approximation. This leads to strong non-adiabatic coupling resulting in large changes of the energies and lifetimes of the quantum levels compared to the values obtained in the Born-Oppenheimer or even the adiabatic levels of approximation. The non-adiabatic calculations of Quadrelli, Dressler, and Wolniewicz (1990) [7] (hereinafter QDW) for the three highest vibrational levels (υ = 44, 45, and 46) of the EF ¹Σ_g⁺ state of D₂ predicted an enormous increase of the lifetimes upon excitation of just one quantum of rotational motion. However, although our experimental results for these levels just below the n = 2 dissociation limit do show a strong increase in lifetime, the non-adiabatic lifetimes calculated by QDW are longer than experiment by as much as three orders of magnitude. In their work on isotopomers of hydrogen QDW and Yu and Dressler (1994) [5] published extensive summary tables of ab initio non-adiabatic coupling data. We present a technique which allows us to use their summary data to calculate approximate non-adiabatic ab initio lifetimes. The results reconcile our observed lifetimes with the non-adiabatic coupling from those previous ab initio calculations and also provide a detailed quantitative and qualitative understanding of the unusual rotational dependence of the lifetimes of these very highly excited levels. We also test the current technique by calculating the lifetimes of other levels involved in interactions with these EF levels and by calculating the lifetimes of the EF υ = 33 level of H₂, for which no corresponding level exists in the Born-Oppenheimer or adiabatic approximations.     

Massive Radiation via Tunneling in a BTZ Black Hole

Hawking radiation can usefully be viewed as a semi-classical tunneling process that originates at the black hole horizon. Massive radiation from a BTZ black hole is investigated. The conservation of energy implies the effect of self-gravitation. Viewed as a tunneling process, the emission spectrum derivates from the pure thermal spectrum, but it is consistent with an underlying unitary theory. The result is the same as that of massless particles.     

Four-parametric regular black hole solution

We present a regular class of exact black hole solutions of the Einstein equations coupled with a nonlinear electrodynamics source. For weak fields the nonlinear electrodynamics becomes the Maxwell theory, and asymptotically the solutions behave as the Reissner–Nordström one. The class is endowed with four parameters, which can be thought of as the mass m, charge q, and a sort of dipole and quadrupole moments and , respectively. For 3, 4, and |q|2s _c m the corresponding solutions are regular charged black holes. For = 3, they also satisfy the weak energy condition. For = = 0 we recover the Reissner–Nordström singular solution and for = 3, = 4 the family includes a previous regular black hole reported by the authors.     

Physical and electrical characteristics of a high-k Yb2O3 gate dielectric

High-k ytterbium oxide (Yb₂O₃) gate dielectrics were deposited on Si substrate by reactive sputtering. The structural features of these films after postdeposition annealing treatment were studied by X-ray diffraction and X-ray photoelectron spectroscopy. It is found that the Yb₂O₃ gate dielectrics annealed at 700 °C exhibit a larger capacitance value, a lower frequency dispersion and a smaller hysteresis voltage in C-V curves compared with other annealing temperatures. They also show negligible charge trapping under high constant voltage stress. This phenomenon is mainly attributed to the decrease in the amorphous silica thickness.