共查询到20条相似文献,搜索用时 15 毫秒
1.
SHU Wei-Xing YU Hong-Wei LI Fei WU Pu-Xun REN Zhong-Zhou 《理论物理通讯》2006,46(1):87-90
Although quantum field theory allows the local energy density negative, it also places severe restrictions on the negative energy. One of the restrictions is the quantum energy inequality (QEI), in which the energy density is averaged over time, or space, or over space and time. By now temporal QEIs have been established for various quantum fields, but less work has been done for the spacetime quantum energy inequality. In this paper we deal with the free Rarita-Schwinger field and present a quantum inequality bound on the energy density averaged over space and time. Comparison with the QEI for the Rarita-Schwinger field shows that the lower bound is the same with the QEI. At the same time, we find the quantum inequality for the Rarita-Schwinger field is weaker than those for the scalar and Dirac fields. This fact gives further support to the conjecture that the more freedom the field has, the more easily the field displays negative energy density and the weaker the quantum inequality becomes. 相似文献
2.
Rarita-Schwinger (RS) quantum free field is reexamined in the context of deformation quantization (DQ). It is interesting
to consider this alternative for the specific case of the spin 3/2 field because DQ avoids the problem of dealing from the
beginning with the extra degrees of freedom which appears in the conventional canonical quantization. It is found out that
the subsidiary condition does not introduce any change either in the Wigner function or in other aspects of the Weyl-Wigner-Groenewold-Moyal
formalism, such as: the Stratonovich-Weyl quantizer and normal ordering, in relation to de Dirac field case. The RS propagator
is also calculated within this framework. 相似文献
3.
We examine the energy density produced by a state vector which is the superposition of three single electron states in the Dirac field in the four-dimensional Minkowski spacetime. We derive the conditions on which the energy density can be negative. We then show that the energy density satisfies two quantum inequalities in the ultrarelativistic limit. 相似文献
4.
This paper investigates the quantum Dirac field in n+1-dimensional flat
spacetime and derives a lower bound in the form of quantum
inequality on the energy density averaged
against spacetime sampling functions. The state-independent quantum inequality
derived in the present paper is
similar to the temporal quantum energy inequality and
it is stronger for massive
field than for massless one. It also
presents the concrete results of the quantum inequality in 2 and
4-dimensional spacetimes. 相似文献
5.
We obtain a lower bound on the spacetime-weighted average of the energy density for the scalar field in four-dimensional flat spacetime. The bound takes the form of a quantum inequality. The inequality does not rely on the quantum state and its form is only related to the weights, namely the spacetime sampling functions which are assumed to be smooth, positive and compactly supported. It is found that the inequality is just equal to the temporal quantum energy inequality. When the characteristic length of the temporal sampling function tends to zero, the lower bound becomes divergent. This is consistent with the fact that the spatial restriction on negative energy density does not exist in four-dimensional spacetime. 相似文献
6.
ZHENG Shi-Biao 《理论物理通讯》2001,(11)
A simplified scheme is proposed for the test of quantum nonlocality of the type described by Hardy [Phys.Rev.Left.71 (1993) 1665].In the scheme two appropriately prepared atoms are simultaneously sent through a cavity and dispersively interact with the cavity field.Then state-selective measurements are performed on these atoms,which may reveal quantum nonlocality without using Bell inequality.We also propose a simple scheme for the generation of multi-atom entangled states.`` 相似文献
7.
ZHENG Shi-Biao 《理论物理通讯》2001,36(5):547-549
A simplified scheme is proposed for the test of quantum nonlocality of the type described by Hardy [Phys.Rev.Left.71 (1993) 1665] .In the scheme two appropriately prepared atoms are simultaneously sent through a cavity and dispersively interact with the cavity field.Then state-selective measurements are performed on these atoms,which may reveal quantum nonlocality without using Bell inequality.We also propose a simple scheme for the generation of multi-atom entangled states. 相似文献
8.
We discuss the prominence of Hopf algebras in recent progress in Quantum Field Theory. In particular, we will consider the Hopf algebra of renormalization, whose antipode turned out to be the key to a conceptual understanding of the subtraction procedure. We shall then describe several occurrences of this, or closely related Hopf algebras, in other mathematical domains, such as foliations, Runge-Kutta methods, iterated integrals and multiple zeta values. We emphasize the unifying role which the Butcher group, discovered in the study of numerical integration of ordinary differential equations, plays in QFT. 相似文献
9.
10.
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. 相似文献
11.
The usual formulations of quantum field theory in Minkowski spacetime make crucial use of features—such as Poincaré invariance
and the existence of a preferred vacuum state—that are very special to Minkowski spacetime. In order to generalize the formulation
of quantum field theory to arbitrary globally hyperbolic curved spacetimes, it is essential that the theory be formulated
in an entirely local and covariant manner, without assuming the presence of a preferred state. We propose a new framework
for quantum field theory, in which the existence of an Operator Product Expansion (OPE) is elevated to a fundamental status,
and, in essence, all of the properties of the quantum field theory are determined by its OPE. We provide general axioms for
the OPE coefficients of a quantum field theory. These include a local and covariance assumption (implying that the quantum
field theory is constructed in a local and covariant manner from the spacetime metric and other background structure, such
as time and space orientations), a microlocal spectrum condition, an “associativity” condition, and the requirement that the
coefficient of the identity in the OPE of the product of a field with its adjoint have positive scaling degree. We prove curved
spacetime versions of the spin-statistics theorem and the PCT theorem. Some potentially significant further implications of
our new viewpoint on quantum field theory are discussed. 相似文献
12.
Quantum fields are well known to violate the weak energy condition of general relativity: the renormalised energy density
at any given point is unbounded from below as a function of the quantum state. By contrast, for the scalar and electromagnetic
fields it has been shown that weighted averages of the energy density along timelike curves satisfy “quantum weak energy inequalities”
(QWEIs) which constitute lower bounds on these quantities. Previously, Dirac QWEIs have been obtained only for massless fields
in two-dimensional spacetimes. In this paper we establish QWEIs for the Dirac and Majorana fields of mass m≥ 0 on general four-dimensional globally hyperbolic spacetimes, averaging along arbitrary smooth timelike curves with respect
to any of a large class of smooth compactly supported positive weights. Our proof makes essential use of the microlocal characterisation
of the class of Hadamard states, for which the energy density may be defined by point-splitting.
Received: 21 May 2001 / Accepted: 23 August 2001 相似文献
13.
L. H. Ford 《International Journal of Theoretical Physics》2003,42(6):1219-1227
The singularity theorems of classical general relativity are briefly reviewed. The extent to which their conclusions might still apply when quantum theory is taken into account is discussed. There are two distinct quantum loopholes: quantum violation of the classical energy conditions, and the presence of quantum fluctuations of the spacetime geometry. The possible significance of each is discussed. 相似文献
14.
Recent observations of the Cosmic Microwave Background, Supernovae and Sloan Digital Sky Survey (SDSS) show that our universe has a critical energy density, and roughly 2/3 of it is dark energy, which drives the accelerating expansion of the cosmos. In view of the astrophysical data, we find that the equation of state parameter of the dark energy lies in a narrow range around w = −1. In this paper, we construct a cosmology model with a Rarita-Schwinger field to realize the equation of state parameter w < −1 or w > −1 and discuss its stability. 相似文献
15.
Edward B. Manoukian 《Fortschritte der Physik》1991,39(7):501-530
The paper deals with a recent systematic study of the propagation of relativistic quantum particles in spacetime. This study was a reaction to the overwhelming number of experiments dealing with the localization of not only massive but also of photons by detectors. The method of study is based on a configuration unitarity expansion of the vacuum-to-vacuum transition amplitudes as, massive and massless, particles propagate between emitters and detectors. Topics treated are the amplitudes of propagation from one time-space coordinate to another, limiting velocities of particles and their reconciliations with relativity, emergence of particles into cones in detection regions versus the direction of their moments, stimulated emissions by external sources in spacetime, scattering theory in quantum field theory in configuration space, and finally a spacetime for mulation of closed-time path for multi-particle states. 相似文献
16.
Howard E. Brandt 《Foundations of Physics Letters》1998,11(3):265-275
Maximal-acceleration invariant quantum fields are formulated in terms of the differential geometric structure of the spacetime tangent bundle. The simple special case is considered of a flat Minkowski space-time for which the bundle is also flat. The field is shown to have a physically based Planck-scale effective regularization and a spectral cutoff at the Planck mass. 相似文献
17.
V. M. González-Robles 《Foundations of Physics》2003,33(5):839-853
We make use of natural induction to propose, following John Ju Sakurai, a generalization of Bell's inequality for two spin s=n/2(n=1,2,...) particle systems in a singlet state. We have found that for any finite integer or half-integer spin Bell's inequality is violated when the terms in the inequality are calculated from a quantum mechanical point of view. In the final expression for this inequality the two members therein are expressed in terms of a single parameter . Violation occurs for in some interval of the form (,/2) where parameter becomes closer and closer to /2, as the spin grows, that is, the greater the spin number the size of the interval in which violation occurs diminishes to zero. Bell's inequality is a relationship among observables that discriminates between Einstein's locality principle and the non-local point of view of orthodox quantum mechanics. So our conclusion may also be stated by saying that for large spin numbers the non-local and local points of view agree. 相似文献
18.
19.
It is proved for a Haag–Araki–Kastler quantum field theory, that gravitation reduces the correlations in the vacuum state. Secondly, we prove Bell's inequalities by nuclearity assumptions. The so-called -content of certain compact mappings restricts the size of the set of measurements which violate Bell's inequalities. 相似文献
20.
Bounds on One-Dimensional Exchange Energies with Application to Lowest Landau Band Quantum Mechanics
By means of a generalization of the Fefferman–de la Llave decomposition we derive a general lower bound on the interaction energy of one-dimensional quantum systems. We apply this result to a specific class of lowest Landau band wave functions. 相似文献