Resolved-sideband laser cooling in a penning trap

We report the laser cooling of a single $^{40}\text{Ca}^+$ ion in a Penning trap to the motional ground state in one dimension. Cooling is performed in the strong binding limit on the 729-nm electric quadrupole $S_{1/2}\leftrightarrow D_{5/2}$ transition, broadened by a quench laser coupling the $D_{5/2}$ and $P_{3/2}$ levels. We find the final ground state occupation to be $98\pm1\%$. We measure the heating rate of the trap to be very low with $\dot{\bar{n}}\approx 0.3\pm0.2\textrm{s}^{-1}$ for trap frequencies from $150-400\textrm{kHz}$, consistent with the large ion-electrode distance.Comment: 4 pages, 6 figures. Accepted: Phys. Rev. Lett. (2016) http://journals.aps.org/prl/accepted/b6074YefH1115b5881f77975417a6ae0bc9f652a

Dissolved organic carbon dynamics in a UK podzolic moorland catchment: linking storm hydrochemistry, flow path analysis and sorption experiments

Better knowledge of spatial and temporal delivery of dissolved organic carbon (DOC) in small catchments is required to understand the mechanisms behind reported long-term changes in C fluxes from some peatlands. We monitored two storms with contrasting seasons and antecedent conditions in a small upland UK moorland catchment. We examined DOC concentrations and specific UV absorbance (SUVA at 285 nm), together with solute concentrations required to undertake end-member mixing analyses to define dominant flow paths contributing to streamflow. This was combined with laboratory soil-solution equilibrations. We aimed to resolve how seasonal biogeochemical processing of DOC and flowpath changes in organo-mineral soils combine to affect DOC exported via the stream. An August storm following a dry period gave maximum DOC concentration of 10 mg l<sup>−1</sup>. Small DOC:DON ratios (16–28) and SUVA (2.7–3.6 l mg<sup>−1</sup> m<sup>−1</sup>) was attributed to filtration of aromatic compounds associated with up to 53% B horizon flow contributions. This selective filtration of high SUVA DOC was reproduced in the experimental batch equilibration system. For a November storm, wetter antecedent soil conditions led to enhanced soil connectivity with the stream and seven times greater DOC stream-load (maximum concentration 16 mg l<sup>−1</sup>). This storm had a 63% O horizon flow contribution at its peak, limited B horizon buffering and consequently more aromatic DOC (SUVA 3.9–4.5 l mg<sup>−1</sup> m<sup>−1</sup> and DOC:DON ratio 35–43). We suggest that simple mixing of waters from different flow paths cannot alone explain the differences in DOC compositions between August and November and biogeochemical processing of DOC is required to fully explain the observed stream DOC dynamics. This preliminary evidence is in contrast to other studies proposing hydrological controls on the nature of DOC delivered to streams. Although our study is based only on two storms of very different hydrological and biogeochemical periods, this should promote wider study of DOC biogeochemical alteration in headwaters so that this be better incorporated in modelling to predict the impacts of changes in DOC delivery to, and fate in, aquatic systems

Sideband cooling of small ion Coulomb crystals in a Penning trap

We have recently demonstrated the laser cooling of a single 40 Ca + ion to the motional ground state in a Penning trap using the resolved-sideband cooling technique on the electric quadrupole transition S 1/2 ↔ D 5/2 . Here we report on the extension of this technique to small ion Coulomb crystals made of two or three 40 Ca + ions. Efficient cooling of the axial motion is achieved outside the Lamb-Dicke regime on a two-ion string along the magnetic field axis as well as on two- and three-ion planar crystals. Complex sideband cooling sequences are required in order to cool both axial degrees of freedom simultaneously. We measure a mean excitation after cooling of n COM for the centre of mass (COM) mode and n B for the breathing mode of the two-ion string with corresponding heating rates of 11(2)s -1 and 1(1)s -1 at a trap frequency of 162 kHz. The occupation of the ground state of the axial modes (n tilt = n COM = 0) is above 75% for the two-ion planar crystal and the associated heating rates 0.8(5)s -1 at a trap frequency of 355 kHz

Control of the conformations of ion Coulomb crystals in a Penning trap

Laser-cooled atomic ions form ordered structures in radiofrequency ion traps and in Penning traps. Here we demonstrate in a Penning trap the creation and manipulation of a wide variety of ion Coulomb crystals formed from small numbers of ions. The configuration can be changed from a linear string, through intermediate geometries, to a planar structure. The transition from a linear string to a zigzag geometry is observed for the first time in a Penning trap. The conformations of the crystals are set by the applied trap potential and the laser parameters, and agree with simulations. These simulations indicate that the rotation frequency of a small crystal is mainly determined by the laser parameters, independent of the number of ions and the axial confinement strength. This system has potential applications for quantum simulation, quantum information processing and tests of fundamental physics models from quantum field theory to cosmology

Cross-scale analysis of social-ecological systems:Policy options appraisal for delivering NetZero and other environmental objectives in Scotland

Public policy confronts complex, contested, wicked problems such as climate and biodiversity crises with challenges of how issues are framed, analysed, codified, and interpreted. Social-ecological systems provide an analytical framework that couples the biosphere and technosphere, recognising biophysical limits and emphasising the importance of critical reflection within policy decision-making. Conducting policy-options appraisals is increasingly seen as a transdisciplinary research-policy endeavour with researchers engaging policy actors in an extended peer community (post-normal science). This paper presents a case study of analysis undertaken with researchers, policy analysts, policy makers and other stakeholders to support decisions on how to implement future agriculture support in Scotland, so that the policy programme better delivers across social, economic and environmental objectives. The key change being considered in the future agricultural support programme is Enhanced Conditionality (EC) where the level of financial support provided to farm-businesses will depend on their undertaking agri-environmental measures that deliver against the key priorities of reducing greenhouse gas emissions and reversing biodiversity losses. The paper outlines the policy context within which the EC options appraisal takes place – highlighting how EC is a crucial component in making the wider suite of policy measures work. The transdisciplinary approach, Quantitative Story Telling (QST) is presented, emerging from decision support, participatory research, and post-normal science for policy domains. The stages of QST highlight the importance of analysis that underpins any quantification (decision on how issues are framed and what it included in the analysis) and the expectation that research outputs with be deliberated on with, and interpreted from, stakeholder perspectives. The project specific analyses are outlined, combining top-down options appraisal of how macro-policy decisions could constrain EC and bottom-up analysis of potential uptake and effectiveness of EC measures, undertaken in inter-disciplinary workshops with domain experts from biodiversity, soils and waters. The paper highlights challenges for implementation and evaluation at meso-scale with interactions between farm-businesses and catchment, landscape and regional objectives. The conclusions of the analysis, in policy terms, are that EC presents an opportunity to significantly realign how agricultural land management is conducted in Scotland, so that it is more effective in delivering climate change and biodiversity objectives, but there are formidable challenges in resolving the policy “sudoku”. Meso-scale issues are likely to mean the need to integrate alternative modelling paradigms such as spatial, empirical agent-based modelling (ABM) into policy option appraisals. By taking multi-scale, social-ecological systems perspectives on EC it has been possible to identify key policy decisions at a range of scales on which the success of EC will depend, to have a realistic understanding of how effective the EC measures might be in heterogenous Scottish environments and what are the likely barriers to uptake. The analysis also highlighted where outcomes of the policy change are likely to be challenging to monitor-evaluate; and where there are dependencies between farm-businesses that mean EC measures need to be supplemented with mechanisms that (1) promote cooperation between land managers and (2) identify and respond to agreed local priorities. The value of the participatory QST process was in making sure the analyses being undertaken were salient and the outputs seen as credible – but the challenges of interpreting necessarily complex outputs remain. The greatest value of QST may be that it provides a structured way to navigate complexity with policy makers rather than seeking to control or eliminate it.</p

Cross-scale analysis of social-ecological systems:Policy options appraisal for delivering NetZero and other environmental objectives in Scotland

Public policy confronts complex, contested, wicked problems such as climate and biodiversity crises with challenges of how issues are framed, analysed, codified, and interpreted. Social-ecological systems provide an analytical framework that couples the biosphere and technosphere, recognising biophysical limits and emphasising the importance of critical reflection within policy decision-making. Conducting policy-options appraisals is increasingly seen as a transdisciplinary research-policy endeavour with researchers engaging policy actors in an extended peer community (post-normal science). This paper presents a case study of analysis undertaken with researchers, policy analysts, policy makers and other stakeholders to support decisions on how to implement future agriculture support in Scotland, so that the policy programme better delivers across social, economic and environmental objectives. The key change being considered in the future agricultural support programme is Enhanced Conditionality (EC) where the level of financial support provided to farm-businesses will depend on their undertaking agri-environmental measures that deliver against the key priorities of reducing greenhouse gas emissions and reversing biodiversity losses. The paper outlines the policy context within which the EC options appraisal takes place – highlighting how EC is a crucial component in making the wider suite of policy measures work. The transdisciplinary approach, Quantitative Story Telling (QST) is presented, emerging from decision support, participatory research, and post-normal science for policy domains. The stages of QST highlight the importance of analysis that underpins any quantification (decision on how issues are framed and what it included in the analysis) and the expectation that research outputs with be deliberated on with, and interpreted from, stakeholder perspectives. The project specific analyses are outlined, combining top-down options appraisal of how macro-policy decisions could constrain EC and bottom-up analysis of potential uptake and effectiveness of EC measures, undertaken in inter-disciplinary workshops with domain experts from biodiversity, soils and waters. The paper highlights challenges for implementation and evaluation at meso-scale with interactions between farm-businesses and catchment, landscape and regional objectives. The conclusions of the analysis, in policy terms, are that EC presents an opportunity to significantly realign how agricultural land management is conducted in Scotland, so that it is more effective in delivering climate change and biodiversity objectives, but there are formidable challenges in resolving the policy “sudoku”. Meso-scale issues are likely to mean the need to integrate alternative modelling paradigms such as spatial, empirical agent-based modelling (ABM) into policy option appraisals. By taking multi-scale, social-ecological systems perspectives on EC it has been possible to identify key policy decisions at a range of scales on which the success of EC will depend, to have a realistic understanding of how effective the EC measures might be in heterogenous Scottish environments and what are the likely barriers to uptake. The analysis also highlighted where outcomes of the policy change are likely to be challenging to monitor-evaluate; and where there are dependencies between farm-businesses that mean EC measures need to be supplemented with mechanisms that (1) promote cooperation between land managers and (2) identify and respond to agreed local priorities. The value of the participatory QST process was in making sure the analyses being undertaken were salient and the outputs seen as credible – but the challenges of interpreting necessarily complex outputs remain. The greatest value of QST may be that it provides a structured way to navigate complexity with policy makers rather than seeking to control or eliminate it.</p