1,225 research outputs found
Towards phase-coherent caloritronics in superconducting circuits
The emerging field of phase-coherent caloritronics (from the Latin word
"calor", i.e., heat) is based on the possibility to control heat currents using
the phase difference of the superconducting order parameter. The goal is to
design and implement thermal devices able to master energy transfer with a
degree of accuracy approaching the one reached for charge transport by
contemporary electronic components. This can be obtained by exploiting the
macroscopic quantum coherence intrinsic to superconducting condensates, which
manifests itself through the Josephson and the proximity effect. Here, we
review recent experimental results obtained in the realization of heat
interferometers and thermal rectifiers, and discuss a few proposals for exotic
non-linear phase-coherent caloritronic devices, such as thermal transistors,
solid-state memories, phase-coherent heat splitters, microwave refrigerators,
thermal engines and heat valves. Besides being very attractive from the
fundamental physics point of view, these systems are expected to have a vast
impact on many cryogenic microcircuits requiring energy management, and
possibly lay the first stone for the foundation of electronic thermal logic.Comment: 11 pages, 6 colour figure
Determining All Universal Tilers
A universal tiler is a convex polyhedron whose every cross-section tiles the
plane. In this paper, we introduce a certain slight-rotating operation for
cross-sections of pentahedra. Based on a selected initial cross-section and by
applying the slight-rotating operation suitably, we prove that a convex
polyhedron is a universal tiler if and only if it is a tetrahedron or a
triangular prism.Comment: 18 pages, 12 figure
Free-energy bounds for hierarchical spin models
In this paper we study two non-mean-field spin models built on a hierarchical
lattice: The hierarchical Edward-Anderson model (HEA) of a spin glass, and
Dyson's hierarchical model (DHM) of a ferromagnet. For the HEA, we prove the
existence of the thermodynamic limit of the free energy and the
replica-symmetry-breaking (RSB) free-energy bounds previously derived for the
Sherrington-Kirkpatrick model of a spin glass. These RSB mean-field bounds are
exact only if the order-parameter fluctuations (OPF) vanish: Given that such
fluctuations are not negligible in non-mean-field models, we develop a novel
strategy to tackle part of OPF in hierarchical models. The method is based on
absorbing part of OPF of a block of spins into an effective Hamiltonian of the
underlying spin blocks. We illustrate this method for DHM and show that,
compared to the mean-field bound for the free energy, it provides a tighter
non-mean-field bound, with a critical temperature closer to the exact one. To
extend this method to the HEA model, a suitable generalization of Griffith's
correlation inequalities for Ising ferromagnets is needed: Since correlation
inequalities for spin glasses are still an open topic, we leave the extension
of this method to hierarchical spin glasses as a future perspective
INFOSEC in a Basket, 2004-2013
Topical and methodological diversity are key strengths of Information Systems (IS) research. To the extent that an IS sub-field such as IS security (hereafter, InfoSec) employs varied methods to examine various topics, the sub-field can claim strength through diversity. We conducted a systematic review of ten years of 85 InfoSec studies published in the IS Senior Scholars Basket of eight journals. We find that InfoSec researchers have employed a variety of quantitative and qualitative methods to study a variety of topics; that some journals published papers based on some methods and InfoSec topics more than others; that many methods are underutilized as applied to some topics; and that topics addressing the organizational/managerial and inter-organizational levels of analysis are understudied. We conclude that InfoSec research is maturing, yet abundant opportunities still exist to conduct further research aimed at building stronger theories and offering stronger implications for InfoSec practice
- …