Implementation of Cavity Squeezing of a Collective Atomic Spin

We squeeze unconditionally the collective spin of a dilute ensemble of laser-cooled rubidium-87 atoms using their interaction with a driven optical resonator. The shape and size of the resulting spin uncertainty region are well described by a simple analytical model [M.H.S., I.D.L., V.V., arXiv:0911.3936] through two orders of magnitude in the effective interaction strength, without free parameters. We deterministically generate states with up to 5.6(6) dB of metrologically relevant spin squeezing on the canonical rubidium-87 hyperfine clock transition.Comment: 4 pages, 2 figures. To be published in Phys. Rev. Lett. Some additional details and clarified wording in response to referee comments. Figures and results unchange

Squeezing the Collective Spin of a Dilute Atomic Ensemble by Cavity Feedback

We propose and analyze a simple method to squeeze dynamically and unconditionally the collective spin of a dilute atomic ensemble by interaction with a driven mode of an optical resonator, as recently demonstrated [I. D. L., M. H. S., and V. V., Phys. Rev. Lett. 104, 073602 (2010)]. We show that substantial squeezing can be achieved in the regime of strong collective ensemble-resonator coupling. The squeezing is ultimately limited either by photon emission into free space or by the curvature of the Bloch sphere. We derive both limits and show where each prevails.Comment: 4 pages, 2 figures. Minor revision. To appear in Phys. Rev.

L’Accord général sur le commerce des services (AGCS) : règles propres à des secteurs particuliers

L'Accord général sur le commerce des services (AGCS), qui est entré en vigueur le 1er janvier 1995 et est administré par l'Organisation mondiale du commerce (OMC), est le premier accord multilatéral sur le commerce des services. Il a mis en place un ensemble de règles normatives s'appliquant en principe à tous les secteurs de services. Il comporte également des régimes complémentaires et particuliers au regard des secteurs suivants : services financiers ; télécommunications ; transport aérien ; mouvement des personnes physiques. Ces régimes plus particuliers se sont avérés nécessaires en raison de la complexité et des particularités afférentes à ces secteurs. Le présent article offre une analyse approfondie et détaillée des règles particulières s'appliquant à ces secteurs. Bien que nombreuses et fort significatives, notamment en ce qui a trait au secteur des services financiers et au secteur des télécommunications, et contrairement aux règles générales de l'AGCS, elles ont jusqu'à présent fait l'objet de peu d'analyse de fond. Une présentation des éléments de contexte pertinents permettant de comprendre la spécificité de ces secteurs et les raisons pour lesquelles des régimes particuliers ont été négociés accompagne l'analyse juridique. En conclusion, d'autres secteurs où des problématiques particulières surgissent et relativement auxquels, dans le contexte du nouveau cycle de négociations sur les services débuté en 2000, la négociation de règles particulières et plus spécifiques pourrait s'avérer nécessaire ou utile sont mis en évidence.The General Agreement on Trade in Services (GATS), which came into force on January 1, 1995 and is under the administration of the World Trade Organization (WTO), is the first multilateral agreement on trade in services. In it has been implemented a framework of basic obligations that apply in principle to all service sectors. It also includes in complementary annexes various specific commitments with regard to the following sectors : financial services, telecommunications, air-transport services and the movement of natural persons. These more specific commitments proved necessary owing to the complexity and particularities found in these sectors. This paper offers an in-depth and detailed analysis of the specific rules applying to these sectors. While numerous and quite significant— especially in the financial services and telecommunications sectors— and contrary to the general rules under GATS, until now they have been the subject of few in-depth analyses. The legal analysis is accompanied with a presentation of the relative contextual environment that sheds light on the particular nature of these sectors and the reasons why such specific commitments were negotiated. In concluding, further emphasis is put upon other sectors where specific issues arise and for which — within the context of the new round of negotiations on services begun in the year 2000 - the negotiation of special and more specific rules could prove to be necessary or useful

Evaluating Marketing Channel Options for Small-Scale Fruit and Vegetable Producers: Case Study Evidence from Central New York

An investigation of the relative costs and benefits of marketing channels used by typical small-scale diversified vegetable crop producers is conducted. Using case study evidence from four small farms in Central New York, this study compares the performance of wholesale and direct marketing channels, including how the factors of risk, owner and paid labor, price, lifestyle preferences, and sales volume interact to impact optimal market channel selection. Given the highly perishable nature of the crops grown, along with the risks and potential sales volume of particular channels, a combination of different marketing channels is needed to maximize overall firm performance. Accordingly, a ranking system is developed to summarize the major firm-specific factors across channels and to prioritize those channels with the greatest opportunity for success based on individual firm preferences.Marketing channel, small-scale, fruit and vegetable producers, case study, Agribusiness, Crop Production/Industries, Financial Economics,

Evaluating Marketing Channel Options for Small-Scale Fruit and Vegetable Producers

An investigation of the relative costs and benefits of marketing channels used by typical smallscale diversified vegetable crop producers is conducted. Using case study evidence from four small farms in Central New York, this study compares the performance of wholesale and direct marketing channels, including how the factors of risk, owner and paid labor, price, lifestyle preferences, and sales volume interact to impact optimal market channel selection. Given the highly perishable nature of the crops grown, along with the risks and potential sales volume of particular channels, a combination of different marketing channels is needed to maximize overall firm performance. Accordingly, a ranking system is developed to summarize the major firm-specific factors across channels and to prioritize those channels with the greatest opportunity for success based on individual firm preferences.local food, marketing, wholesale, direct, marketing channels, economic evaluation, Agribusiness, Community/Rural/Urban Development, Crop Production/Industries, Demand and Price Analysis, Production Economics,

Pinning an Ion with an Intracavity Optical Lattice

We report one-dimensional pinning of a single ion by an optical lattice. The lattice potential is produced by a standing-wave cavity along the rf-field-free axis of a linear Paul trap. The ion's localization is detected by measuring its fluorescence when excited by standing-wave fields with the same period, but different spatial phases. The experiments agree with an analytical model of the localization process, which we test against numerical simulations. For the best localization achieved, the ion's average coupling to the cavity field is enhanced from 50% to 81(3)% of its maximum possible value, and we infer that the ion is bound in a lattice well with over 97% probability.Comment: 5 pages, 4 figures; Text edited for clarity, results unchange

States of an Ensemble of Two-Level Atoms with Reduced Quantum Uncertainty

We generate entangled states of an ensemble of 5*10^4 rubidium-87 atoms by optical quantum nondemolition measurement. The resonator-enhanced measurement leaves the atomic ensemble, prepared in a superposition of hyperfine clock levels, in a squeezed spin state. By comparing the resulting reduction of quantum projection noise (up to 8.8(8) dB) with the concomitant reduction of coherence, we demonstrate a clock input state with spectroscopic sensitivity 3.0(8) dB beyond the standard quantum limit.Comment: Letter (4 pages, 3 figures) followed by Auxiliary Material (10 pages, 6 figures). Minor changes in presentation and analysis of data. Significant expansion of Auxiliary Material. Broken images fixe

Mountain trail formation and the active walker model

We extend the active walker model to address the formation of paths on gradients, which have been observed to have a zigzag form. Our extension includes a new rule which prohibits direct descent or ascent on steep inclines, simulating aversion to falling. Further augmentation of the model stops walkers from changing direction very rapidly as that would likely lead to a fall. The extended model predicts paths with qualitatively similar forms to the observed trails, but only if the terms suppressing sudden direction changes are included. The need to include terms into the model that stop rapid direction change when simulating mountain trails indicates that a similar rule should also be included in the standard active walker model.Comment: Introduction improved. Analysis of discretization errors added. Calculations from alternative scheme include