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arXiv 1706.06280gr-qcphysics.class-phphysics.optics
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电动力学中本构张量的有效度量和协变描述

Effective metrics and a fully covariant description of constitutive tensors in electrodynamics

Sebastian Schuster, Matt Visser

摘要:

使用电磁学来研究模拟时空相当于考虑当给定的(Meta)材料将提供模拟时空模型时的一致性条件,或者-反之亦然--表征可以用(Meta)材料建模的给定度量。虽然一致性条件本身现在是众所周知的和研究的,但一旦它们被满足,度量的形式就不存在了。这个问题很容易回答,只要保持这两个研究领域的形式主义尽可能接近。虽然介质电动力学的完全协变公式已经存在了很长一段时间,但它们通常被(3+1)或6维形式主义所抛弃。在这里,我们将使用完全统一和完全协变的方法。这使得我们甚至可以将有效度规存在的相容性条件推广到平坦时空电动力学之外的任意背景度规。我们还展示了如何熟悉的矩阵介电常数$ε$,磁导率$μ^{-1}$,和磁电效应$ζ$可以被看作是三个独立的部分Bel分解的本构张量$Z^{abcd}$,即,正交分解的分量与给定的观测器与四速度$V^a$。最后,我们将使用摩尔-彭罗斯伪逆和密切相关的伪行列式,然后获得所需的重建的有效度量的介电常数张量$ε^{ab}$,磁导率张量$[μ^{-1}]^{ab}$,和磁电张量$ζ^{ab}$,作为一个显式函数$g_{\text{eff}}(ε,μ^{-1},ζ)$。

英文摘要:

Using electromagnetism to study analogue space-times is tantamount to considering consistency conditions for when a given (meta-)material would provide an analogue space-time model or --- vice versa --- characterizing which given metric could be modelled with a (meta-)material. While the consistency conditions themselves are by now well known and studied, the form the metric takes once they are satisfied is not. This question is mostly easily answered by keeping the formalisms of the two research fields here in contact as close to each other as possible. While fully covariant formulations of the electrodynamics of media have been around for a long while, they are usually abandoned for (3+1)- or 6-dimensional formalisms. Here we shall use the fully unified and fully covariant approach. This enables us even to generalize the consistency conditions for the existence of an effective metric to arbitrary background metrics beyond flat space-time electrodynamics. We also show how the familiar matrices for permittivity $ε$, permeability $μ^{-1}$, and magneto-electric effects $ζ$ can be seen as the three independent pieces of the Bel decomposition for the constitutive tensor $Z^{abcd}$, i.e., the components of an orthogonal decomposition with respect to a given observer with four-velocity $V^a$. Finally, we shall use the Moore--Penrose pseudo-inverse and the closely related pseudo-determinant to then gain the desired reconstruction of the effective metric in terms of the permittivity tensor $ε^{ab}$, the permeability tensor $[μ^{-1}]^{ab}$, and the magneto-electric tensor $ζ^{ab}$, as an explicit function $g_{\text{eff}}(ε,μ^{-1},ζ)$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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