Gravitinos tunneling from black holes

Black hole radiation of gravitinos is investigated as the classically forbidden tunneling of spin-3/2 fermions through an event horizon. We calculate directly that all four spin states of the gravitino yield the same emission temperature, and the Unruh temperature in a Rindler spacetime as well as the Hawking temperature for a Kerr–Newman charged rotating black hole are retrieved. This confirms the robustness of the tunneling formalism in a wide range of applications.     

Comments on anomaly versus WKB/tunneling methods for calculating Unruh radiation

In this Letter we make a critique of, and comparison between, the anomaly method and WKB/tunneling method for obtaining radiation from non-trivial spacetime backgrounds. We focus on Rindler spacetime (the spacetime of an accelerating observer) and the associated Unruh radiation since this is the prototype of the phenomena of radiation from a spacetime, and it is the simplest model for making clear subtle points in the tunneling and anomaly methods. Our analysis leads to the following conclusions: (i) neither the consistent and covariant anomaly methods gives the correct Unruh temperature for Rindler spacetime and in some cases (e.g. de Sitter spacetime) the consistent and covariant methods disagree with one another; (ii) the tunneling method can be applied in all cases, but it has a previously unnoticed temporal contribution which must be accounted for in order to obtain the correct temperature.     

On the incompleteness of the Unruh fermion modes in the Minkowski space

It has been shown that boost modes of two-dimensional fermions on a light cone are expressed in terms of the Dirac delta function of a complex argument. Therefore, the decomposition of integrals over the entire range of the boost parameter into parts is inapplicable and the Unruh quantization is valid only in the double Rindler wedge, rather than in the entire Minkowski space. This means that the Unruh “effect” is absent for any statistics of particles. Thus, both the theoretical predictions and numerous proposals of experiments based on the assumption of the existence of this effect are unfounded.     

Does the Unruh effect exist?

It is shown that quantization on the Fulling modes presupposes that the field vanishes on the spatial boundaries of the Rindler manifold. For this reason, Rindler space is physically unrelated with Minkowski space and the state of a Rindler observer cannot be described by the equilibrium density matrix with the Fulling-Unruh temperature. Therefore it is pointless to talk about an Unruh effect. The question of the behavior of an accelerated detector in the physical formulation of the problem remains open. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 12, 861–866 (25 June 1997)     

Hawking Radiation of Dirac Particles on Rindler Horizon to a Uniformly Accelerating Observer

Following the method of Damour and Ruffini, the Hawking radiation of Dirac particles on Rindler horison to a uniformly accelerating observer is studied this paper. The temperature on Rindler horizon surface and the thermal spectrum formula of Dirac particles are obtained. The result is discussed.     

Quantum parameter estimation in the Unruh–DeWitt detector model

Relativistic effects on the precision of quantum metrology for particle detectors, such as two-level atoms are studied. The quantum Fisher information is used to estimate the phase sensitivity of atoms in non-inertial motions or in gravitational fields. The Unruh–DeWitt model is applicable to the investigation of the dynamics of a uniformly accelerated atom weakly coupled to a massless scalar vacuum field. When a measuring device is in the same relativistic motion as the atom, the dynamical behavior of quantum Fisher information as a function of Rindler proper time is obtained. It is found out that monotonic decrease in phase sensitivity is characteristic of dynamics of relativistic quantum estimation. The origin of the decay of quantum Fisher information is the thermal bath that the accelerated detector finds itself in due to the Unruh effect. To improve relativistic quantum metrology, we reasonably take into account two reflecting plane boundaries perpendicular to each other. The presence of the reflecting boundary can shield the detector from the thermal bath in some sense.     

Unruh effect and holography

We study the Unruh effect on the dynamics of quarks and mesons in the context of AdS₅/CFT₄ correspondence. We adopt an AdS₅ metric with the boundary Rindler horizon extending into a bulk Rindler-like horizon, which yields the thermodynamics with Unruh temperature verified by computing the boundary stress tensor. We then embed in it a probe fundamental string and a D7 brane in such a way that they become the dual of an accelerated quark and a meson in Minkowski space, respectively. Using the standard procedure of holographic renormalization, we calculate the chiral condensate, and also the spectral functions for both the accelerated quark and meson. Especially, we extract the corresponding strength of random force of the Langevin dynamics and observe that it can characterize the phase transition of meson melting. This result raises an issue toward a formulation of complementarity principle for the Rindler horizon. We find most of the dynamical features are qualitatively similar to the ones in the thermal bath dual to the AdS black hole background, though they could be quite different quantitatively.     

动态Rindler时空中Dirac旋量粒子的四分量波函数及Hawbing-Unruh热效应

在动态Rindler时空中对Dirac旋量粒子的动力学行为进行了研究,得到Dirac粒子四分量波函数的显式表示。同时还发现,对于一个作变加速直线运动的Rindler观察者存在一个随时间而变的视界,并将探测到随时间而变的热辐射,辐射温度正比于观察者的瞬时加速度,从而再一次证实了动态Rindler效应的存在。     

The coordinate coherent states approach revisited

We revisit the coordinate coherent states approach through two different quantization procedures in the quantum field theory on the noncommutative Minkowski plane. The first procedure, which is based on the normal commutation relation between an annihilation and creation operators, deduces that a point mass can be described by a Gaussian function instead of the usual Dirac delta function. However, we argue this specific quantization by adopting the canonical one (based on the canonical commutation relation between a field and its conjugate momentum) and show that a point mass should still be described by the Dirac delta function, which implies that the concept of point particles is still valid when we deal with the noncommutativity by following the coordinate coherent states approach. In order to investigate the dependence on quantization procedures, we apply the two quantization procedures to the Unruh effect and Hawking radiation and find that they give rise to significantly different results. Under the first quantization procedure, the Unruh temperature and Unruh spectrum are not deformed by noncommutativity, but the Hawking temperature is deformed by noncommutativity while the radiation specturm is untack. However, under the second quantization procedure, the Unruh temperature and Hawking temperature are untack but the both spectra are modified by an effective greybody (deformed) factor.     

Entropy of a Rindler Observer

We compute the entropy of a Rindler particle-detector (observer) in the presence of a quantum field in the Minkowski vacuum state; due to the Unruh effect, the observer is immersed in a thermal bath at a temperature proportional to its proper acceleration.     

Delay time computation for relativistic tunneling particles

We study the tunneling zone solutions of a one-dimensional electrostatic potential for the relativistic (Dirac to Klein–Gordon) wave equation when the incoming wave packet exhibits the possibility of being almost totally transmitted through the barrier. The transmission probabilities, the phase times and the dwell times for the proposed relativistic dynamics are obtained and the conditions for the occurrence of accelerated tunneling transmission are all quantified. We show that, in some limiting cases, the analytical difficulties that arise when the stationary phase method is employed for obtaining phase (traversal) tunneling times are all overcome. Lessons concerning the phenomenology of the relativistic tunneling suggest revealing insights into condensed-matter experiments using electrostatic barriers for which the accelerated tunneling effect can be observed. PACS 03.65.Xp     

Ion trap simulations of quantum fields in an expanding universe

We propose an experiment in which the phonon excitation of ion(s) in a trap, with a trap frequency exponentially modulated at rate kappa, exhibits a thermal spectrum with an "Unruh" temperature given by k(B)T=Planck kappa. We discuss the similarities of this experiment to the response of detectors in a de Sitter universe and the usual Unruh effect for uniformly accelerated detectors. We demonstrate a new Unruh effect for detectors that respond to antinormally ordered moments using the ion's first blue sideband transition.     

The SO(3,1)-Gauge Invariant Approach to Fermions on Rindler Spacetime

We try to explicitly derive the Lorentz-gauge covariant Dirac equation,in terms of pseudo-orthonormal bases,on Rindler spacetime and to work out,with all the necessary coefficients,the respective closed-form solutions,in both Dirac and Weyl representations.     

Hawking Radiation of Dirac Particles on Rindler Horizon to a Uniformly Accelerating Observer

Following the method of Damour and Ruffini, the Hawking radiation of Dirac particles on Rindler horizonto a uniformly accelerating observer is studied in this paper. The temperature on Rindler horizon surface and the thermalspectrum formula of Dirac particles are obtained. The result is discussed.     

Dirac Quantum Field Theory in Rindler Spacetime

The dynamical properties of Dirac particles inRindler spacetime are investigated. It is shown that thevacuum state of the Dirac field in Minkowski spacetimeappears to be a thermal state for a Rindler observer, and the usual thermal equilibriumstate of the Dirac field in Minkowski spacetime is aquasithermal equilibrium state, which is timeindependent and characterized by two quasi-temperatureparameters for a Rindler observer.     

Fermions tunneling of higher-dimensional Kerr–Anti-de Sitter black hole with one rotational parameter

The 1/2 spin fermions tunneling at the horizon of n-dimensional Kerr–Anti-de Sitter black hole with one rotational parameter is researched via semi-classical approximation method, and the Hawking temperature and fermions tunneling rate are obtained in this Letter. Using a new method, the semi-classical Hamilton–Jacobi equation is gotten from the Dirac equation in this Letter, and the work makes several quantum tunneling theories more harmonious.     

Two Uniqueness Results on the Unruh Effect¶and on PCT-Symmetry

The Unruh effect and a closely related form of PCT-symmetry have been proved in general for finite-component Wightman fields by Bisognano and Wichmann. While this result incorporates most of the fields occurring in four-dimensional high energy physics, there still are field theories of interest that are not covered (e.g., low-dimensional anyon fields and infinite-component fields). From the spectrum condition, Borchers has derived a couple of commutation relations which ”almost, but only almost“ imply the Unruh effect and PCT-symmetry. We show that this result does imply Unruh effect and PCT-symmetry provided that the operators involved in Borchers' commutation relations act geometrically on a local net of observables. Received: 15 October 2000 / Accepted: 6 March 2001     

Tunneling across dilaton–axion black holes

In this work we study both charged and uncharged particles tunneling across the horizon of spherically symmetric dilaton–axion black holes using Parikh–Wilczek tunneling formalism. Such black hole solutions have much significance in string theory based models. For different choices of the dilaton and axion couplings with the electromagnetic field, we show that the tunneling probability depends on the difference between initial and final entropies of the black hole. Our results, which agree with similar results obtained for other classes of black holes, further confirm the usefulness of Parikh–Wilczek formalism to understand Hawking radiation. The emission spectrum is shown to agree with a purely thermal spectrum only in the leading order. The modification of the proportionality factor in the area–entropy relation in the Bekenstein–Hawking formula has been determined.     

Experimental simulation of the Unruh effect on an NMR quantum simulator

The Unruh effect is one of the most fundamental manifestations of the fact that the particle content of a field theory is observer dependent. However, there has been so far no experimental verification of this effect, as the associated temperatures lie far below any observable threshold. Recently, physical phenomena, which are of great experimental challenge, have been investigated by quantum simulations in various fields. Here we perform a proof-of-principle simulation of the evolution of fermionic modes under the Unruh effect with a nuclear magnetic resonance(NMR) quantum simulator. By the quantum simulator, we experimentally demonstrate the behavior of Unruh temperature with acceleration, and we further investigate the quantum correlations quantified by quantum discord between two fermionic modes as seen by two relatively accelerated observers. It is shown that the quantum correlations can be created by the Unruh effect from the classically correlated states. Our work may provide a promising way to explore the quantum physics of accelerated systems.