共查询到20条相似文献,搜索用时 15 毫秒
1.
We study the behaviour of Dirac current in expanding spacetime with Schrödinger and de Sitter form for the evolution of the scale-factor. The study is made to understand the particle-antiparticle rotation and the evolution of quantum vacuum leading to particle production in such spacetime. 相似文献
2.
K S Virbhadra 《Pramana》1992,38(1):31-35
The components of the energy-momentum pseudotensors of Einstein, Tolman, Landau and Lifshitz, and Møller are evaluated for the Vaidya radiating spacetime. These pseudotensors are found to be traceless for this spacetime. The pseudotensors of Einstein and Tolman give exactly same result for all their components. Unlike in the case of the Kerr-Newman field, the pseudotensor of Møller gives the same energy as given by that of the Einstein, Tolman or Landau and Lifshitz. 相似文献
3.
Particle production in curved spacetime has been discussed through the method of complex time WKB approximation. We consider
Dirac equation in non-flat spacetime to understand particle production as particle-antiparticle rotation. The method is also
generalized to understand particle production through parametric resonance. To understand the method of CWKB we consider particle
production in Kasner spacetime as an example. 相似文献
4.
We consider the teleportation in the background of Kerr-Newman spacetime. Because of the Hawking effect, the fidelity of the teleportation is reduced. The results also show the fidelity is closely related to the mass, charge and rotating velocity of the black hole: high fidelity can be reached for massive, slowly rotating Kerr-Newman black holes. 相似文献
5.
We study the pairwise entanglement of a three-qubit spins in the XXZ model, and teleport an unknown state using the spin chain in the thermal equilibrium as a quantum channel. The effects of coupling strength, magnetic field, the anisotropy and temperature on the entanglement and fidelity are investigated. We find that the ferromagnetic spin chain is suitable for quantum teleportation, while the anti-ferromagnetic one is not. We give the maximal average fidelity, and the condition under which the maximal average fidelity is obtained. In addition, the relation between the entanglement and fidelity is studied, and we find that the considered entanglement cannot completely reflect the fidelity. 相似文献
6.
In this work a number of examples are used to illustrate uniqueness of physical prediction of the Dirac theory in a curved and a flat spacetime. Dirac Hamiltonians in arbitrary, including time‐dependent, gravitational fields uniquely determine physical characteristics of quantum‐mechanical systems irrespective of the choice of the tetrad fields. Direct spin‐rotation coupling that occurs with a certain choice of tetrads does not manifest itself in final physical characteristics of the systems and therefore does not represent a physically relevant effect. 相似文献
7.
The stability problem of the Rindler spacetime is carefully
studies by using the scalar wave perturbation. Using two different
coordinate systems, the scalar wave equation is investigated. The
results are different in the two cases. They are analysed and
compared with each other in detail. The following conclusions are
obtained: (a) the Rindler spacetime as a whole is not stable; (b) the
Rindler spacetime can exist stably only as part of the Minkowski
spacetime, and the Minkowski spacetime can be a real entity
independently; (c) there are some defects for the scalar wave
equation written by the Rindler coordinates, and it is unsuitable for
the investigation of the stability properties of the Rindler
spacetime. All these results may shed some light on the stability
properties of the Schwarzschild black hole. It is natural and
reasonable for one to infer that: (a) perhaps the Regge--Wheeler
equation is not sufficient to determine
the stable properties; (b) the Schwarzschild black hole as a whole
might be really unstable; (c) the Kruskal spacetime is stable and can
exist as a real physical entity; whereas the Schwarzschild black hole
can occur only as part of the Kruskal spacetime. 相似文献
8.
9.
We investigate the creation rate of massive spin-1 bosons in the de Sitter universe by a time-dependent electric field via the Duffin–Kemmer–Petiau (DKP) equation. Complete solutions are given by the Whittaker functions and particle creation rate is computed by using the Bogoliubov transformation technique. We analyze the influence of the electric field on the particle creation rate for the strong and vanishing electric fields. We show that the electric field amplifies the creation rate of charged, massive spin-1 particles. This effect is analyzed by considering similar calculations performed for scalar and spin-1/2 particles. 相似文献
10.
We extend to higher dimensions an earlier work of Santos regarding junction conditions for a spherical fluid distribution
with heat flux and an electromagnetic field. It is observed that the pressure at the surface of distribution does not vanish
when the heat flow is present. 相似文献
11.
In the context of quantum field theories in curved spacetime, we compute the effective action of the transition amplitude from vacuum to vacuum in the presence of an external gravitational field. The imaginary part of the resulted effective action determines the probability of vacuum decay via a quantum tunneling process, giving the rate and spectrum of particle creations. We show that (i) the gravitational field polarizes the vacuum and discretizes its spectrum; (ii) vacuum gains gravitational energy by such a polarization. On the basis of gravitational vacuum polarization, we discuss the quantum origin of vacuum decay in curved spacetime as pair-creations of particles and anti-particles. The thermal spectrum of particle creations is attributed to (i) the CPT invariance of pair-creations (annihilations) from (into) vacuum and (ii) vacuum acts as a reserve with the temperature determined by gravitational energy-gain. 相似文献
12.
The quantum entropies due to the scalar and Dirac fields are investigated in a pure de Sitter spacetime. The leading divergent terms in both cases are regularized by the Pauli-Villars scheme. It is shown that the explosive entropies can be renormalized according to the Bekenstein-Hawking formula. 相似文献
13.
An exact solution is obtained for coupled dilaton and electromagnetic field in a cylindrically symmetric spacetime where an
axial magnetic field as well as a radial electric field both are present. Depending on the choice of the arbitrary constants
our solution reduces either to dilatonic gravity with pure electric field or to that with pure magnetic field. In the first
case we have a curvature singularity at a finite distance from the axis indicating the existence of the boundary of a charged
cylinder which may represent the source of the electric field. For the second case we have a singularity on the axis. When
the dilaton field is absent the electromagnetic field disappears in both the cases. Whereas the contrary is not true. It is
further shown that light rays except for those proceeding in the radial direction are either trapped or escape to infinity
depending on the magnitudes of certain constant parameters as well as on the nature of the electromagnetic field. Nature of
circular geodesics is also studied in the presence of dilaton field in the cylindrically symmetric spacetime. 相似文献
14.
We use Fermi coordinates to calculate the canonical partition function for an ideal gas in a circular geodesic orbit in Schwarzschild
spacetime. To test the validity of the results we prove theorems for limiting cases. We recover the Newtonian gas law subject
only to tidal forces in the Newtonian limit. Additionally we recover the special relativistic gas law as the radius of the
orbit increases to infinity. We also discuss how the method can be extended to the non ideal gas case. 相似文献
15.
Jieci Wang 《Annals of Physics》2010,325(6):1190-500
It is shown that the projective measurements made by Bob who locates near the event horizon of the Schwarzschild black hole will create entangled particles detected by Alice who stays stationary at the asymptotically flat region. It is found that the degree of entanglement decreases as the frequency of the detected particles increases and approaches to zero as the frequency ωk → ∞. It is also noted that the degree of entanglement increases as the Hawking temperature increases. Especially, the particle state is unentangled when the Hawking temperature is zero and approaches a maximally entangled Bell state when the black hole evaporates completely. 相似文献
16.
Some properties related to the NUT--Taub-like spacetime,
such as the surface of infinite red-shift, horizon, singularity
and the area of the NUT--Taub-like black hole are discussed.
Furthermore, the geodesics in the NUT--Taub-like spacetime are
obtained in some special cases. Specifically, the circular orbits
for a massive particle are derived, which can reduce to the cases
of the Schwarzschild spacetime and the NUT--Taub spacetime when
m*=0 and m*\ll M, respectively. 相似文献
17.
We emphasize the close relationship between zeta function methods and arbitrary spectral cutoff regularizations in curved spacetime. This yields, on the one hand, a physically sound and mathematically rigorous justification of the standard zeta function regularization at one loop and, on the other hand, a natural generalization of this method to higher loops. In particular, to any Feynman diagram is associated a generalized meromorphic zeta function. For the one-loop vacuum diagram, it is directly related to the usual spectral zeta function. To any loop order, the renormalized amplitudes can be read off from the pole structure of the generalized zeta functions. We focus on scalar field theories and illustrate the general formalism by explicit calculations at one-loop and two-loop orders, including a two-loop evaluation of the conformal anomaly. 相似文献
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20.
In the framework of open quantum systems, we study the internal dynamics of both freely falling and static two-level atoms interacting with quantized conformally coupled massless scalar field in de Sitter spacetime. We find that the atomic transition rates depend on both the nature of de Sitter spacetime and the motion of atoms, interestingly the steady states for both cases are always driven to being purely thermal, regardless of the atomic initial states. This thermalization phenomenon is structurally similar to what happens to an elementary quantum system immersed in a thermal field, and thus reveals the thermal nature of de Sitter spacetime. Besides, we find that the thermal baths will drive the entanglement shared by the freely falling atom (the static atom) and its auxiliary partner, a same two-level atom which is isolated from external fields, to being sudden death, and the proper time for the entanglement to be extinguished is computed. We also analyze that such thermalization and disentanglement phenomena, in principle, could be understood from the perspective of table-top simulation experiment. 相似文献