Squeezed cooling of mechanical motion beyond the resolved-sideband limit

Cavity optomechanics provides a unique platform for controlling micromechanical systems by means of optical fields that crosses the classical-quantum boundary to achieve solid foundations for quantum technologies. Currently, optomechanical resonators have become promising candidates for the development of precisely controlled nano-motors, ultrasensitive sensors and robust quantum information processors. For all these applications, a crucial requirement is to cool the mechanical resonators down to their quantum ground states. In this paper, we present a novel cooling scheme to further cool a micromechanical resonator via the noise squeezing effect. One quadrature in such a resonator can be squeezed to induce enhanced fluctuation in the other, "heated" quadrature, which can then be used to cool the mechanical motion via conventional optomechanical coupling. Our theoretical analysis and numerical calculations demonstrate that this squeeze-and-cool mechanism offers a quick technique for deeply cooling a macroscopic mechanical resonator to an unprecedented temperature region below the zero-point fluctuations.Comment: 5 pages, 4 figure

Receiprocity and Downward Wage Rigidity

The employment relationship is to a large extent characterized by incomplete contracts, in which workers have a considerable degree of discretion over the choice of their work effort. This discretion at work kicks in the potential importance of “gift exchange” or reciprocity between workers and employers in their employment relationship. Built on the seminal work of Akerlof (1980), this paper adopts a social norm approach to model reciprocity in labor markets and theoretically derives two versions of downward wage rigidity. The first version explains why employers may adopt a high wage policy far above the competitive level. This version is not a novel finding in the existing literature and is mainly served as a benchmark for later comparison in the current paper. Our main contribution lies in the second version in which not nly may employers adopt a high wage policy far above the competitive level, but one can also account for the asymmetric behavior of wages and explain why employers are hesitant about wage cuts in the presence of negative shocks. We argue that this second and stronger version of downward wage rigidity has moved the efficiency wage theory a step forward.Reciprocity, Downward Wage Rigidity, Social Norm, Efficiency Wage

The Firm as a Community Explaining Asymmetric Behavior and Downward Rigidity of Wages

This paper models the firm as a community à la Akerlof (1980) to account for asymmetric behavior, and in particular, downward rigidity of wages. It is shown that, through social interaction among workers in the firm community, wage cuts can give rise to a large, discontinuous fall in labor productivity (known as “catastrophe”). Furthermore, this large fall in labor productivity will persist or display inertia (known as “hysteresis”) even if the wages are restored to the pre-cut level and beyond. Our catastrophe/hysteresis finding with respect to wage cuts can rationalize the downward rigidity of wage behavior, and is consistent with the interview evidence of fragile worker morale emphasized by Bewley (1999) and others in explaining why employers are sensitive to and refrain from cutting worker pay.Wage rigidity, Firm community, Catastrophe, Hysteresis

Generalized Clifford Algebras as Algebras in Suitable Symmetric Linear Gr-Categories

By viewing Clifford algebras as algebras in some suitable symmetric Gr-categories, Albuquerque and Majid were able to give a new derivation of some well known results about Clifford algebras and to generalize them. Along the same line, Bulacu observed that Clifford algebras are weak Hopf algebras in the aforementioned categories and obtained other interesting properties. The aim of this paper is to study generalized Clifford algebras in a similar manner and extend the results of Albuquerque, Majid and Bulacu to the generalized setting. In particular, by taking full advantage of the gauge transformations in symmetric linear Gr-categories, we derive the decomposition theorem and provide categorical weak Hopf structures for generalized Clifford algebras in a conceptual and simpler manner

Progressive albitisation in the "Migmatite Creek" region, Weekeroo Inlier, Curnamona.

Albitisation is pervasive and intense in the Curnamona Province. Most FeO-Cu-Au-U-REE deposits are associated with sodic alteration or albitisation (alkaline alteration) worldwide. The minor Cu-Au-U-REE mineralisation occurs in the large albitisation system in the Curnamona Province. Progressive albitisation allows us to demonstrate the mobility of metals linked to mineralisation in the Migmatite Creek, Weekeroo Inliers, Curnamona Province. Lithological and thematic mapping of albitisation intensities distinguishing low-, medium-, and high- grade albitisation was carried out in the Migmatite Creek area using ArcGIS mapping tools. Progressive albitisation was investigated using whole rock, electron microprobe and Laser Ablation ICPMS analytical methods to establish major, trace and rare earth element variation on a range of scales in bulk samples and individual mineral phases. Albitisation is structurally controlled by OD3 antiformal folds and development of a network of breccias creating pathways of fluid flow. Intensities of albitisation decrease from antiformal to synformal fold hinges. Mass balance estimates, using isocons allow a semi-quantitative view of the evolution of fluid and rock compositions and the mobility of elements during progressive albitisation. The evolution of temperature was independently identified by using mineral geothermometers. Mobility of rare earth element (REE) resulted in extreme changes of REE patterns during progressive albitisation. The initial albitisation fluids were identified in the range of hypersaline (approximately 30 wt% equi. NaCl) with the NaCl rich - CO₂ - KCl - MgCl₂ ± Al(OH)[SUBSCRIPT]x ± CaCl₂ - H₂O was related to regional fluids of metamorphism and migmatisation. 87 % of Eu and 99% of La were removed from psammites to fluids during high intensity albitisation. Most of the siderophile elements, Ni, Co, Cr, Mn and Mo, as well as Zn, Ba and Sr, were removed from unaltered rock to the fluids in the area. The chemical equilibria of fluid/rock reaction were completely attained between quartz and albite during high–medium intensity albitisation against uncompleted equilibria in low intensity albitisation. New albite +quartz + accessory minerals replaced the original quartz + feldspars + biotite + magnetite assemblages. Progressive albitisation resulted in evolution of fluids and then lead to a secondary stage biotite alteration and a weak quartz alteration (inserted quartz veins). Fe – U – REE elements were extremely removed from all types of lithologies (metasediments and pegmatites and amphibolites) during progressive albitisation. A highly charged, metal fluid was formed during albitisation. Albitisation has great potential as a source process for mineralisation and from its characteristics shows links to the IOCG-REE systems.Thesis (M.Sc.) - University of Adelaide, School of Earth and Environmental Sciences, 200

Generalized Synchronization with Uncertain Parameters of Nonlinear Dynamic System via Adaptive Control

An adaptive control scheme is developed to study the generalized adaptive chaos synchronization with uncertain chaotic parameters behavior between two identical chaotic dynamic systems. This generalized adaptive chaos synchronization controller is designed based on Lyapunov stability theory and an analytic expression of the adaptive controller with its update laws of uncertain chaotic parameters is shown. The generalized adaptive synchronization with uncertain parameters between two identical new Lorenz-Stenflo systems is taken as three examples to show the effectiveness of the proposed method. The numerical simulations are shown to verify the results

Nonlinear Dynamic Analysis and Synchronization of Four-Dimensional Lorenz-Stenflo System and Its Circuit Experimental Implementation

Recently many chaotic systems’ circuits are designed to generate phenomenon of chaos signals. The ability to synchronize chaotic circuits opens a great number of ways to use them in application signals masking. In this paper, first a new nonlinear chaotic dynamical system had be design, analyze and build circuit. Second, using GYC, partial region stability theory is applied to adaptive control for two identical chaotic systems with uncertain parameters. The results of numerical simulation are performed to verify examples of the proposed nonlinear controllers