Numerical study of stretched smectic-Aelastomer sheets

Abstract

We present a numerical study of stretching monodomain smectic-A elastomer sheets, computed using the finite element method. When stretched parallel to their smectic layer normal the smectic layers are unstable to a transition to a buckled state. We model macroscopic deformations by replacing the microscopic energy with a coarse grained effective free energy that accounts for the fine-scale layer buckling. We augment this model with a term to describe the energy of deforming buckled layers, which is necessary to reproduce the experimentally observed Poisson ratios postbuckling. We examine the spatial distribution of the microstructure phases for various stretching angles relative to the layer normal and for different length-to-width aspect ratios. When stretching parallel to the layer normal the majority of the sample forms a bidirectionally buckled microstructure, except at the clamps where a unidirectionally buckled microstructure is predicted. When stretching at small inclinations to the layer normal the phase of the sample is sensitive to the aspect ratio of the sample, with the bidirectionally buckled phase persistent to large angles only for small aspect ratios. We relate these theoretical results to experiments on smectic-A elastomers.

Role of thermal field in entanglement harvesting between two accelerated Unruh-DeWitt detectors

“…We use the prescription as provided in [49] for the construction of the Green's functions and follow the formulation of articles [40,42] for entanglement harvesting. We arrive at the same assertions that entanglement extraction is possible only for the anti-parallelly accelerated detectors and not for the parallelly accelerated ones, and also encounter the phenomena of degrading entanglement extraction with increasing temperature of the thermal bath [43,44]. However, here the situation is a bit more complicated, as we have observed that this degradation is happening in the low acceleration regimes and above a certain value of acceleration thermal bath has an enhancing effect on the entanglement harvesting for the two detectors with equal magnitude of acceleration in both (1 + 1) and (1 + 3) dimensions.…”

“…On the other hand, the effects of a thermal bath on the entanglement harvesting remains equally interesting, see [43] and [44]. This environment is much more practical as in nature the background in general is thermal.…”

“…In this regard, it may be mentioned that the thermal nature of fields has already been included in various investigations related to Unruh-De Witt detectors; like calculation of response functions in case of single detector [45][46][47][48] and two entangled detectors [49]. In both [43] and [44] it is predicted that the entanglement extraction gets depleted with increasing temperature of the thermal field. Then it will be quite fascinating to study the situation of entanglement harvesting for accelerated observers interacting with thermal fields, which is not there in the literature up to our knowledge.…”

Extraction of genuine tripartite entanglement from the vacuum

“…Here we opt to work directly in the Schrödinger picture (although this formalism can also be performed in the interaction picture; see [10] for example) and so we will take F sym = F sym free + F sym int as given by Eqs. (7,8).…”

“…The problem was fixed in [5] by adding more field modes and the idea was further developed, providing a useful formalism for the analytical treatment of point-like detectors interacting with the vacuum. This formalism has been extensively used to study various scenarios in the harvesting of entanglement [4][5][6] and more general quantum correlations [7] in the case of bipartite harvesting (i.e. two detectors).…”