Optical and evaporative cooling of cesium atoms in the gravito-optical surface trap

We report on cooling of an atomic cesium gas closely above an evanescent-wave atom mirror. At high densitities, optical cooling based on inelastic reflections is found to be limited by a density-dependent excess temperature and trap loss due to ultracold collisions involving repulsive molecular states. Nevertheless, very good starting conditions for subsequent evaporative cooling are obtained. Our first evaporation experiments show a temperature reduction from 10muK down to 300nK along with a gain in phase-space density of almost two orders of magnitude.Comment: 8 pages, 6 figures, submitted to Journal of Modern Optics, special issue "Fundamentals of Quantum Optics V", edited by F. Ehlotzk

how much more and how much better?

Funding Information: We thank two autonomous reviewers and the team of Climate Policy editors for their excellent comments and suggestions. We are thankful for the financial support of the German Federal Ministry of Economic Cooperation and Development (BMZ) for this research. The research was done independently, BMZ had no role in the preparation, analysis or writing of this article or its outcomes. Publisher Copyright: © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.Formal deliberations for the new collective quantified goal on climate finance began at COP26 in Glasgow. This Perspectives article aims to inform this process by discussing the potential size and nature of is post-2025 target. We argue that the climate finance system around the current target to mobilise US$100 billion per year to support developing countries has been fraught with difficulties, and that it would be ineffective to simply increase the climate finance target without addressing these difficulties. Therefore, we identify and discuss five priority elements for negotiations: the relation to Article 2.1(c) of the Paris Agreement; the adaptation-mitigation balance; financial instruments; mobilising private finance; and ‘new and additional’ finance. To increase transparency, accountability, and trust in climate finance under the UNFCCC and to simultaneously allow for the mobilisation of finance at scale, we suggest setting a sub-target for grants. In combination with additional (sub)target(s), this could define an overall new collective quantified goal that is better suited to serve the challenging dual role of mobilising finance at scale and transferring resources to developing countries. Key policy insights: Ambiguous definitions of climate finance and the US$100 billion target allow for multiple interpretations, reducing transparency and trust between countries. Climate finance targets can be interpreted in a dual and sometimes contrasting way: mobilising investment at scale and transferring resources from developed to developing countries. Recognising this duality may help to find common ground for a post-2025 climate finance target. Increasing the climate finance target may prove ineffective without further clarity on private finance mobilisation, the relation to Art. 2.1(c), and other priority elements. More detailed assessments of needs, priorities, costs, and support are needed to inform the post-2025 target and assess climate finance provision effectiveness. A sub-target for grants could increase accountability, trust, and transparency, and target the needs of the most vulnerable developing countries. Negotiations on the post-2025 climate finance target could also consider additional aspects such as access to and prioritisation of finance, and loss and damage.publishersversionpublishe

Barriers to increasing energy efficiency: Evidence from small- and medium-sized enterprises in China

This paper analyzes financial, informational and organizational barriers to energy efficiency investments for small-and medium-sized enterprises (SMEs) in China. Its findings are based on a survey of 480 SMEs in Zhejiang province, and complemented by semi-structured interviews with enterprises contained in the survey sample. Responses reveal that only a minority of SMEs in China actively perform energy saving activities at a significant level. The survey data suggest, further, that informational barriers are the core bottleneck inhibiting energy efficiency improvements in China's SME sector. Financial and organizational barriers also influence a company's energy saving activities, with interview-based evidence stronger than statistical evidence. The interviews point out three additional barriers to energy saving activities: the role of family ownership structures, lax enforcement of government regulations and the absence of government support as well as a lack of skilled labor. More than 40% of enterprises in the sample declared themselves unaware of energy saving equipment or practices in their respective business area, indicating that there are high transaction costs for SMEs to gather, assess, and apply information about energy saving potentials and relevant technologies. One policy implication of the study is that the Chinese government could play a more active role in fostering the dissemination of energy-efficiency related information in the SME sector

Manipulation of spin-polarized atoms in an optical dipole-force trap

Ultracold cesium atoms are stored in a novel dipole-force trap, which provides long storage times of spin polarization and facilitates easy Stern-Gerlach selection. The trap consists of a far red-detuned standing light wave, oriented vertically in the field of gravity. By comparing the trapping of a single magnetic substate (F=4, mF=0) with the simultaneous storage of all sublevels, we measure the decay of spin polarization that results from photon scattering of trap light. We furthermore observe spin precession in an optically induced “fictitious magnetic field”

A Focus on Market Imperfections Can Help Governments to Mobilize Private Investments in Adaptation

Climate change requires significant adaptation of economies, and the largest part of most economies is composed of private sector actors. In this Viewpoint, we argue that it should not be the role of the public sector to cover the full costs of adaptation - which would also typically exceed government's fiscal space. Rather, we suggest that the public sector should set the right conditions to catalyse private investments in adaptation. While the suggestion is not new, we argue that the current focus on generic ‘barriers’ hindering more private investments in adaptation is not expedient. These barriers are descriptive rather than explanatory, sometimes mix cause and effect, and tend to focus on eliminating obstacles, rather than adapting efficiently. Alternatively, we suggest to focus on addressing three market imperfections that give rise to those barriers. In doing so, the overall welfare of society, including the vulnerability of the most marginalized, should be centre-stage. The development of markets should aim to contribute to such welfare - it is not an end in itself. In that sense, our call for a focus on market imperfections is a call for a larger role of public actors, both in developed and developing countries.1. Introduction 2. Barriers to private adaptation investments 3. Addressing market imperfections to eliminate barriers 4. Concluding remarks Acknowledgements Disclosure statement Additional information Reference

Post-2025 climate finance target: how much more and how much better?

Formal deliberations for the new collective quantified goal on climate finance began at COP26 in Glasgow. This Perspectives article aims to inform this process by discussing the potential size and nature of is post-2025 target. We argue that the climate finance system around the current target to mobilise US$100 billion per year to support developing countries has been fraught with difficulties, and that it would be ineffective to simply increase the climate finance target without addressing these difficulties. Therefore, we identify and discuss five priority elements for negotiations: the relation to Article 2.1(c) of the Paris Agreement; the adaptation-mitigation balance; financial instruments; mobilising private finance; and ‘new and additional’ finance. To increase transparency, accountability, and trust in climate finance under the UNFCCC and to simultaneously allow for the mobilisation of finance at scale, we suggest setting a sub-target for grants. In combination with additional (sub)target(s), this could define an overall new collective quantified goal that is better suited to serve the challenging dual role of mobilising finance at scale and transferring resources to developing countries