We derive the solutions of gravitational waves in the future (F) expanding and the past (P) shrinking Kanser spacetimes as well as in the left (L) and right (R) Rindler wedges in the Regge-Wheeler gauge. The solutions for all metric components are obtained in an analytic form in each region. We identify the master variables, which are equivalent to massless scalar fields, to describe the gravitational degrees of freedom for the odd parity and even parity modes under the transformation in the two-dimensional plane symmetric space. Then, the master variables are quantized, and we develop the quantum field theory of the gravitational waves in the F, P, L, and R regions. We demonstrate that the mode functions of the quantized gravitational waves in the left and right Rindler wedges are obtained by an analytic continuation of the left-moving and right-moving wave modes in Kasner spacetime. On the basis of these analyses, we discuss the Unruh effect of quantized gravitational waves for an observer in a uniformly accelerated motion in Minkowski spacetime.
We study the relations of the positive frequency mode functions of Dirac field in 4-dimensional Minkowski spacetime covered with Rindler and Kasner coordinates, and describe the explicit form of the Minkowski vacuum state with the quantum states in Kasner and Rindler regions, and analytically continue the solutions. As a result, we obtain the correspondence of the positive frequency mode functions in Kasner region and Rindler region in a unified manner which derives vacuum entanglement.
We review the geometry of the Rindler space induced by hyperbolic motion in special relativity, and its applications to the calculation of the Unruh effect in flat spacetime, and to the Hawking temperature of the Schwarzschild black hole.
Traditionally the physics of the Unruh effect, i.e. the q.f.t. in the wedges $W_R$ or $W_L$ in Minkowski space is related to the physics in the Rindler Fock space, which is a proplematical strategy. In a careful analysis we show that the correct dual q.f.t. lives rather in the thermal Rindler Hilbert space and turns out to be unitarily equivalent to the corresponding Minkowski space theory in contrast to the Rindler Fock space theory. We show in particular that in thermal Rindler Hilbert space a new sort of objects occurs, viz., quasi-particle/hole creation/annihilation operators of thermal Ri…
A great deal of evidence has been mounting over the years showing a deep connection between acceleration, radiation, and the Unruh effect. Indeed, the fact that the Unruh effect can be codified in the Larmor radiation emitted by the charge was used to propose an experiment to experimentally confirm the existence of the Unruh thermal bath. However, such connection has two puzzling issues: (1) how the quantum Unruh effect can be codified in the classical Larmor radiation and (2) the fundamental role played by zero-Rindler-energy modes of the Unruh thermal bath in such a context. Here we generali…
The interplay between acceleration and radiation harbors remarkable and surprising consequences. One of the most striking is that the Larmor radiation emitted by a charge can be seen as a consequence of the Unruh thermal bath. Indeed, this connection between the Unruh effect and classical bremsstrahlung was used recently to propose an experiment to confirm (as directly as possible) the existence of the Unruh thermal bath. This situation may sound puzzling in two ways: first, because the Unruh effect is a strictly quantum effect while Larmor radiation is a classical one, and second, because of …
We investigate the Unruh effect for a massless scalar field in the two dimensional Minkowski space in the presence of a uniformly accelerated perfect mirror, with the trajectory of the mirror chosen in such a way that the mirror completely masks the Rindler horizon from the space-time region of interest. We find that the characteristic thermodynamical properties of the effect remain unchanged, i.e. the response of a uniformly co-accelerated Unruh detector and the distribution of the Rindler particles retain their thermal form. However, since in this setup there are no unobserved degrees of fre…
We study the temperatures for the circular and drifted Rindler motions by employing the Unruh-DeWitt detector method. In the circular motion, the temperature is increasing along the radius of the circular motion until it reaches the maximum, and then it is decreasing and eventually vanishing at the limit to the radius where the proper acceleration is infinite. In fact, the temperature is proportional to the proper acceleration quadratically near the origin of the circular motion as compared to the usual Unruh effect depending on the linear proper acceleration. On the other hand, in the drifted…
It is well known that the rotational motion does not induce Unruh effect, because the Minkowski vacuum coincides with the vacuum state defined by the pure rotating observers. However, are there Rindler particles carrying orbital angular momentum (OAM), and do they produce observable effect? To answer these questions, we need an accelerated observer having a vortex structure in the transverse dimensions and carrying well-defined OAM. Here we consider the angular momentum characteristics of Unruh effect in the theory of scalar field and electromagnetic field for the first time. We find that the …
If an Unruh-DeWitt detector operates for an infinite proper time along the trajectory of a uniformly accelerated observer in Fock space then induced transition rate of the detector is proportional to Planck distribution. For a realistic detector which operates only for a finite period, the instantaneous transition rate contains both transient and non-transient terms. In particular, the non-transient term contains a residue evaluated at the pole of the two-point function. We show here by considering a massless scalar field that unlike in Fock quantization, the short-distance two-point function …
The energy of a particle moving on a spacetime, in principle, can affect the background metric. The modifications to it depend on the ratio of energy of the particle and the Planck energy, known as rainbow gravity. Here we find the explicit expressions for the coordinate transformations from rainbow Minkowski spacetime to accelerated frame. The corresponding metric is also obtained which we call as rainbow-Rindler metric. So far we are aware of, no body has done it in a concrete manner. Here this is found from the first principle and hence all the parameters are properly identified. The advant…
Existence of Unruh effect is often understood from the property of two-point function along Rindler trajectory where it satisfies KMS condition. In particular, it exhibits the so-called KMS periodicity along imaginary time direction. Corresponding period is then identified with reciprocal of Unruh temperature times Boltzmann constant. We show here that the two-point function including leading order perturbative corrections due to polymer quantization, the quantization method used in loop quantum gravity, violates KMS condition in low-energy regime. This violation is caused by correction terms …
We estimate the transition rates of a uniformly accelerated Unruh-DeWitt detector coupled to a quantum field with reflecting conditions on a boundary plane (a "mirror"). We find that these are essentially indistinguishable from the usual Unruh rates, viz. that the Unruh effect persists in the presence of the mirror. This shows that the Unruh effect is not merely a consequence of the entanglement between left and right Rindler quanta in the Minkowski vacuum. Since in this setup the state of the field in the Rindler wedge is pure, we argue furthermore that the relevant entropy in the Unruh effec…
The thermal spectrum seen by accelerated observers in Minkowski space - known as the Unruh effect - is derived within the tunneling mechanism. This is a new result in this mechanism and it completes the treatment of Unruh effect via tunneling. Both Bose-Einstein and Fermi-Dirac spectrum is derived by considering tunneling of scalar and spin half particles respectively, across the accelerated Rindler horizon. Full solutions of Klein-Gordon and Dirac equations in the Rindler metric are employed to achieve this, instead of approximate solutions.
We analyse the quantization procedure of the spinor field in the Rindler spacetime, showing the boundary conditions that should be imposed to the field, in order to have a well posed theory. Because of these boundary conditions we argue that this construction and the usual one in Minkowski spacetime are qualitatively different and can not be compared and consequently the conventional interpretation of the Unruh effect, that is the thermal nature of the Minkowski vacuum state from the point of view of an accelerated observer, is questionable. We also analyse in detail the Unruh quantization sch…
We canonically quantize the Proca field in the Rindler wedge and compute the total response rate of a uniformly accelerated current interacting with massive vector Rindler particles from the Unruh thermal bath. We explicitly verify that the result obtained is exactly the same as the emission rate of massive vector particles in the Minkowski vacuum as analyzed by inertial observers. Eventually our results are interpreted in terms of the interaction of static electrons coupled to $Z^0$ bosons present in Hawking radiation close to the event horizon of a black hole.
We analyse the quantization procedure of the spinor field in the Rindler spacetime, showing the boundary conditions that should be imposed to the field, in order to have a well posed theory. We then investigate the relationship between this construction and the usual one in Minkowski spacetime. This leads to the concept of "Unruh effect", that is the thermal nature of the Minkowski vacuum state from the point of view of an accelerated observer. It is demostrated that the two constructions are qualitatively different and can not be compared and consequently the conventional interpretation of th…
Mixing transformations for a uniformly accelerated observer (Rindler observer) are analyzed within the quantum field theory framework as a basis for investigating gravitational effects on flavor oscillations. In particular, the case of two charged boson fields with different masses is discussed. In spite of such a minimal setting, the standard Unruh radiation is found to loose its characteristic thermal interpretation due to the interplay between the Bogolubov transformation hiding in field mixing and the one arising from the Rindler spacetime structure. The modified spectrum detected by the R…
We investigate a two-level Unruh-DeWitt detector coupled to a massless scalar field or its proper time derivative in $(1+1)$-dimensional Minkowski spacetime, in a quantum state whose correlation structure across the Rindler horizon mimics the stationary aspects of a firewall that Almheiri et al have argued to ensue in an evaporating black hole spacetime. Within first-order perturbation theory, we show that the detector's response on falling through the horizon is sudden but finite. The difference from the Minkowski vacuum response is proportional to $ω^{-2}\ln(|ω|)$ for the non-derivative dete…
Ultracold fermionic atoms in an optical lattice, with a sudden position-dependent change (a quench) in the effective dispersion relation, have been proposed by Rodríguez-Laguna et al. as an analogue spacetime test of the Unruh effect. We provide new support for this analogue by analysing a massless scalar field on a $(1+1)$-dimensional continuum spacetime with a similar quench: an early time Minkowski region is joined at a constant time surface, representing the quench, to a late time static region in which left and right asymptotically Rindler domains are connected by a smooth negative curvat…
It was suggested by Unruh that a uniformly accelerated detector in vacuum would perceive a noise with a thermal distribution. We obtain a representation of solutions of the wave equation in two dimensions suitable for the Rindler regions. The representation includes the dependence on a parameter. The Unruh field corresponds to a singular limit of the representation.
How to kill the Unruh effect? Very simple, by requiring the Rindler transformation to behave continuously for vanishing acceleration. Then the Unruh effect disappears as we show in the case of the massive scalar quantum field. The main point is that the continuity condition restricts the integral of the mode expansion to the positive energy spectrum, suppressing thus the $β$ - terms of the Bogoliubov transformation.
An equivalence is demonstrated, by an explicit first order quantum calculation, between the Minkowski photon emission rate in the inertial frame for an accelerating charge moving on a Rindler trajectory with additional transverse drift motion and the combined Rindler photon emission and absorption rate of the same charge in the Rindler frame in the presence of the Davies Unruh thermal bath. The equivalence also extends, for the Bremsstrahlung emitted by the same charge as calculated using the machinery of classical electrodynamics. The equivalence is shown to also hold for the case of accelera…
We analyse the response of a spatially extended direction-dependent local quantum system, a detector, moving on the Rindler trajectory of uniform linear acceleration in Minkowski spacetime, and coupled linearly to a quantum scalar field. We consider two spatial profiles: (i) a profile defined in the Fermi-Walker frame of an arbitrarily-accelerating trajectory, generalising the isotropic Lorentz-function profile introduced by Schlicht to include directional dependence; and (ii) a profile defined only for a Rindler trajectory, utilising the associated frame, and confined to a Rindler wedge, but …
The Unruh effect for the rate of emission and absorption of neutral massive Majorana spinor particles -- the most plausible consituents of Dark Matter -- in a Rindler spacetime is thoroughly investigated. The corresponding Bogolyubov coefficients are explicitly calculated and the consistency with Fermi-Dirac statistics and the Pauli principle is actually verified.
We study the matching between the Hawking temperature of a large class of static D-dimensional black holes and the Unruh temperature of the corresponding higher dimensional Rindler spacetime. In order to accomplish this task we find the global embedding of the D-dimensional black holes into a higher dimensional Minkowskian spacetime, called the global embedding Minkowskian spacetime procedure (GEMS procedure). These global embedding transformations are important on their own, since they provide a powerful tool that simplifies the study of black hole physics by working instead, but equivalently…
We describe a new viewpoint on canonical quantization of linear fields on a general curved background that encompasses and generalizes the standard treatment of canonical QFT given in textbooks. Our method permits the construction of pure states and mixed stated with the same technique. We apply our scheme to the study of Rindler QFT and we present a new derivation of the Unruh effect based on invariance arguments.
The incorporation of classical general relativity into quantum field theory yields a surprising result -- thermodynamic particle production. One such phenomenon, known as the Unruh effect, causes empty space to effervesce a thermal bath of particles when viewed by an observer undergoing uniformly accelerated motion. These systems will have a Rindler horizon which produces this Unruh radiation at the Fulling-Davies-Unruh temperature. For accelerated charges, the emission and absorption of this radiation will imprint the FDU temperature on photons emitted in the laboratory. Each of these photons…
We consider coordinate systems adapted to accelerated observers, construct a generalised Rindler metric and then adopt a specific form of it to compute the semiclassical Unruh temperature, using a WKB approximation within a Hamilton Jacobi analysis in the tunneling picture. Corrections to this temperature are next computed by going beyond the usual WKB approximation. A connection of the corrected Unruh temperature with the Hawking temperature is established. This connection is also explained through the method of Global Embedding Minkowski Spacetime (GEMS).
Quantized fields in accelerated frames (Rindler spaces) with emphasis on gauge fields are investigated. Important properties of the dynamics in Rindler spaces are shown to follow from the scale invariance of the corresponding Hamiltonians. Origin and consequences of this extraordinary property of Hamiltonians in Rindler spaces are elucidated. Characteristics of the Unruh radiation, the appearance of a photon condensate and the interaction energy of vector and scalar static charges are discussed and implications for Yang-Mills theories and QCD in Rindler spaces are indicated.
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 R…
It was shown recently that in four dimensions scalar sources with fixed proper acceleration minimally coupled to a massless Klein-Gordon field lead to the same responses when they are (i) uniformly accelerated in Minkowski spacetime (in the inertial vacuum) and (ii) static in the Schwarzschild spacetime (in the Unruh vacuum). Here we show that this equivalence is broken if the spacetime dimension is more than four.
We study the radiative process of two entangled two-level atoms uniformly accelerated in a thermal bath, coupled to a massless scalar field. First, using the positive frequency Wightman function from the Minkowski modes with a Rindler transformation we provide the transition probabilities for the transitions from maximally entangled symmetric and anti-symmetric Bell states to the collective excited state in $(1+1)$ and $(1+3)$ dimensions. We observe a possible case of \emph{anti-Unruh-like} event in these transition probabilities, though the $(1+1)$ and $(1+3)$ dimensional results are not comp…
We present a simple and systematic method to calculate the Rindler noise, which is relevant to the analysis of the Unruh effect, by using the fluctuation-dissipative theorem. To do this, we calculate the dissipative coefficient explicitly from the equations of motion of the detector and the field. This method gives not only the correct answer but also a hint as to the origin of the apparent statistics inversion effect. Moreover, this method is generalized to the Dirac field, by using the fermionic fluctuation-dissipation theorem. We can thus confirm that the fermionic fluctuation-dissipation t…
We investigate the relation between the time-ordered vacuum correlation functions for interacting real scalar fields in Minkowski spacetime and in the Rindler wedge. The correlation functions are constructed perturbatively within the in-in formalism, often employed in calculations in more general spacetimes. We prove to all orders in perturbation theory that the time-ordered vacuum correlation functions can be calculated in the in-in formalism with internal vertices restricted to any Rindler wedge containing the external points. This implies that the Minkowski in-in (or in-out) perturbative ex…
We consider a particle detector model on 1+1-dimensional Minkowski space-time that is accelerated by a constant external acceleration a. The detector is coupled to a massless scalar test field. Due to the Unruh effect, this detector becomes excited even in Minkowski vacuum with a probability proportional to a thermal Bose-Einstein distribution at temperature T=a/2pi in the detector's energy gap. This excitation is usually said to happen upon detection of a Rindler quantum, which is defined by having positive frequency with respect to the detector's proper time instead of inertial time. Using U…
We study the Unruh effect on the dynamics of quarks and mesons in the context of AdS$_5$/CFT$_4$ correspondence. We adopt an AdS$_5$ 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 al…
We studied the change of the nonlocal correlation of the entanglement in Rindler spacetime by showing that the Unruh effect can be interpreted as a noisy quantum channel having a complete positive and trace preserving map with an operator sum representation. It is shown that the entanglement fidelity is obtained in analytic form from the operator sum representation, which agrees well numerically with the entanglement monotone and the entanglement measure obtained previously. Non-zero entropy exchange between the system Q and the region II of the Rindler wedge indicates the nonlocal correlation…
University of York（约克大学）；Universidade Estadual Paulista（圣保罗州立大学）；Universidade de São Paulo（圣保罗大学）；Austrian Academy of Sciences（奥地利科学院）；Rutherford Appleton Laboratory（鲁瑟福阿普尔顿实验室）；University of Strathclyde（思克莱德大学）；Universidade Federal do Pará（帕拉联邦大学）；University of Oxford（牛津大学）
The Unruh effect can be correctly treated only by using the Minkowski quantization and a model of a "particle" detector, not by using the Rindler quantization. The energy produced by a detector accelerated only for a short time can be much larger than the energy needed to change the velocity of the detector. Although the measuring process lasts an infinite time, the production of the energy can be qualitatively explained by a time-energy uncertainty relation.
We study the solutions of the Einstein equations in the presence of a thick infinite slab with constant energy density. When there is an isotropy in the plane of the slab, we find an explicit exact solution that matches with the Rindler and Weyl-Levi-Civita spacetimes outside the slab. We also show that there are solutions that can be matched with general anisotropic Kasner spacetime outside the slab. In any case, it is impossible to avoid the presence of the Kasner type singularities in contrast to the well-known case of spherical symmetry, where by matching the internal Schwarzschild solutio…
We introduce a method to compute particle detector transition probability in spacetime regions of general curved spacetimes provided that the curvature is not above a maximum threshold. In particular we use this method to compare the response of two detectors, one in a spherically symmetric gravitational field and the other one in Rindler spacetime to compare the Unruh and Hawking effects: We study the vacuum response of a detector freely falling through a stationary cavity in a Schwarzschild background as compared with the response of an equivalently accelerated detector traveling through an …
The possibility of chiral symmetry restoration by acceleration is considered. The Thermalization Theorem formalism and the large $N$ limit (with $N$ being the number of pions) are employed to solve the lowest-order approximation to QCD at low energies in Rindler spacetime. It is shown that chiral symmetry is restored for accelerations higher than the critical value $a_c=4πf_π$, with $f_π$ being the pion decay constant. The results are completely analogous to those obtained in the inertial, finite-temperature case, evincing the ontic character of the Unruh effect.
We consider the conformal scalar field theory with $λϕ^4$ self-interaction in Rindler and Minkowskian coordinates at finite temperature planckian distribution for the exact modes. The solution of the one-loop Dyson-Schwinger equation is found to the order in $λ^{3/2}$. Appearance of the thermal (Debye) mass is shown. Unlike the physical mass, the thermal one gives a gap in the energy spectrum in the quantization in the Rindler coordinates. The difference between such calculations in Minkowski and Rindler coordinates for the exact modes is discussed. It is also shown that states with a temperat…
We show that without Lorentz invariance, the Unruh effect does not exist. We use modified dispersion relations and describe in turn: the non-thermal nature of the vacuum (defined in the preferred frame) restricted to the Rindler wedge, the loss of the KMS property of the Wigthman function, the transition amplitudes and transition rates of a uniformaly accelerated detector. This situation seems to contrast with the Hawking radiation of acoustic black holes, which under certain assumptions has been shown to be robust to a breaking of Lorentz symmetry. We explain this discrepancy.
The notions of temperature, entropy and `evaporation', usually associated with spacetimes with horizons, are analyzed using general approach and the following results, applicable to different spacetimes, are obtained at one go. (i) The concept of temperature associated with the horizon is derived in a unified manner and is shown to arise from purely kinematic considerations. (ii) QFT near any horizon is mapped to a conformal field theory without introducing concepts from string theory. (iii) For spherically symmetric spacetimes (in D=1+3) with a horizon at r=l, the partition function has the g…
