79,663 research outputs found
Environment-induced uncertainties on moving mirrors in quantum critical theories via holography
Full text linkEnvironment effects on a -dimensional mirror from the strongly coupled
d-dimensional quantum critical fields with a dynamic exponent in weakly
squeezed states are studied by the holographic approach. The dual description
is a -dimensional probe brane moving in the -dimensional asymptotic
Lifshitz geometry with gravitational wave perturbations. Using the holographic
influence functional method, we find that the large coupling constant of the
fields reduces the position uncertainty of the mirror, but enhances the
momentum uncertainty. As such, the product of the position and momentum
uncertainties is independent of the coupling constant. The proper choices of
the phase of the squeezing parameter might reduce the uncertainties,
nevertheless large values of its amplitude always lead to the larger
uncertainties due to the fact that more quanta are excited as compared with the
corresponding normal vacuum and thermal states. In the squeezed vacuum state,
the position and momentum of the mirror gain maximum uncertainties from the
field at the dynamic exponent when the same squeezed mode is
considered. As for the squeezed thermal state, the contributions of thermal
fluctuations to the uncertainties decrease as the temperature increases in the
case the contributions increase as the
temperature increases. These results are in sharp contrast with those in the
environments of the relativistic free field. Some possible observable effects
are discussed.Comment: This is the version (v2) published in the Annals of Physic
Notes on Properties of Holographic Strange Metals
Full text linkWe investigate properties of holographic strange metals in -dimensions,
generalizing the analysis performed in arXiv:0912.1061. The bulk spacetime is
-dimensional Lifshitz black hole, while the role of charge carriers is
played by probe D-branes. We mainly focus on massless charge carriers, where
most of the results can be obtained analytically. We obtain exact results for
the free energy and calculate the entropy density, the heat capacity as well as
the speed of sound at low temperature. We obtain the DC conductivity and DC
Hall conductivity and find that the DC conductivity takes a universal form in
the large density limit, while the Hall conductivity is also universal in all
dimensions. We also study the resistivity in different limits and clarify the
condition for the linear dependence on the temperature, which is a key feature
of strange metals. We show that our results for the DC conductivity are
consistent with those obtained via Kubo formula and we obtain the charge
diffusion constant analytically. The corresponding properties of massive charge
carriers are also discussed in brief.Comment: 32 pages, minor modification
Strange Metallic Behavior in Anisotropic Background
Full text linkWe continue our analysis on conductivity in the anisotropic background by
employing the D-brane probe technique, where the D-branes play the role of
charge carriers. The DC and AC conductivity for massless charge carriers are
obtained analytically, while interesting curves for the AC conductivity are
also plotted. For massive charge carriers, we calculate the DC and AC
conductivities in the dilute limit and we fix the parameters in the
Einstein-Maxwell-dilaton theory so that the background exhibits the same
scaling behaviors as those for real-world strange metals. The DC conductivity
at finite density is also computed.Comment: 24 pages, 2 figures, minor modification
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