Superfluid qubit systems with ring shaped optical lattices

We study an experimentally feasible qubit system employing neutral atomic currents. Our system is based on bosonic cold atoms trapped in ring-shaped optical lattice potentials. The lattice makes the system strictly one dimensional and it provides the infrastructure to realize a tunable ring-ring interaction. Our implementation combines the low decoherence rates of of neutral cold atoms systems, overcoming single site addressing, with the robustness of topologically protected solid state Josephson flux qubits. Characteristic fluctuations in the magnetic fields affecting Josephson junction based flux qubits are expected to be minimized employing neutral atoms as flux carriers. By breaking the Galilean invariance we demonstrate how atomic currents through the lattice provide a implementation of a qubit. This is realized either by artificially creating a phase slip in a single ring, or by tunnel coupling of two homogeneous ring lattices. The single qubit infrastructure is experimentally investigated with tailored optical potentials. Indeed, we have experimentally realized scaled ring-lattice potentials that could host, in principle, $n\sim 10$ of such ring-qubits, arranged in a stack configuration, along the laser beam propagation axis. An experimentally viable scheme of the two-ring-qubit is discussed, as well. Based on our analysis, we provide protocols to initialize, address, and read-out the qubit.Comment: 14 revtex4-1 pages, 7 figs; to be published in Scientific Report

COVID-19 dashboards have a polarising effect on public trust

You might expect to find that people trust governments more when they release timely information about the pandemic. But Michele Crepaz (NUI Galway) and Gizem Arikan (Trinity College Dublin) find that a lot depends on people’s prior views of the government

Is there a first mover advantage in lobbying? A comparative analysis of how the timing of mobilization affects the influence of interest organizations in 10 polities

The first mover advantage is a critical factor for the productivity of firms that enter new markets. Surprisingly, however, the importance of timing is rarely explored in studies of interest groups and their influence on new policy agendas. In this article, we therefore develop a theory of first mover advantages in lobbying. We argue that especially more resourceful and more highly affected organizations should be able to benefit from early lobbying. Using granular survey data on the timing of lobby efforts by interest groups on Covid-19 related policies in 10 European democracies, we test this novel theory. Our results show that timing is an important predictor of lobbying influence, but that interest groups which are hardly affected by a new policy cannot benefit from early mover advantages in the same way as affected organizations. Moreover, we give evidence for differences in first mover advantages depending on organizational staff resources

Mental health: future challenges

The aim of the Foresight Project on Mental Capital and Wellbeing(www.foresight.gov.uk) is to advise the Government on how to achieve the best possible mental development and mental wellbeing for everyone in the UK in the future. The starting point of the Project was to generate an understanding of the science of mental capital and wellbeing (MCW) and to develop a vision for how the size and nature of the challenges exposed by the Project could evolve over the next 20 years. To make this analysis tractable, the work was divided into five broad areas: ● Mental capital through life ● Learning through life ● Mental health ● Wellbeing and work, and ● Learning difficulties. This report presents the findings for “Mental health” and draws upon a comprehensive assessment of the scientific state-of-the art: overall, around 80 reviews have been commissioned across the five areas. Mental health is a term which is used in a number of different ways and which has unfortunately acquired a substantial stigma in all layers of society. While the main focus of this report is on mental ill-health, positive mental health is also vitally important and is also discussed. However, a more comprehensive consideration of positive mental health has been performed in other parts of the Project (as commissioned reviews and in the context of the future of work. This report starts by looking at the situation today, examining the prevalence of important categories of mental disorder. It then considers the risk and protective factors which influence mental ill health, and determines how its prevalence and impact could change in the future, if existing policies and expenditure remain broadly unchanged. An assessment of strategic choices and interventions to meet the future challenges of mental health (and the challenges associated with the other four areas listed above) will be documented in the final Project report which is due for publication in the autumn of 2008

Conditions for spin squeezing in a cold 87Rb ensemble

We study the conditions for generating spin squeezing via a quantum non-demolition measurement in an ensemble of cold 87Rb atoms. By considering the interaction of atoms in the 5S_{1/2}(F=1) ground state with probe light tuned near the D2 transition, we show that, for large detunings, this system is equivalent to a spin-1/2 system when suitable Zeeman substates and quantum operators are used to define a pseudo-spin. The degree of squeezing is derived for the rubidium system in the presence of scattering causing decoherence and loss. We describe how the system can decohere and lose atoms, and predict as much as 75% spin squeezing for atomic densities typical of optical dipole traps.Comment: 9 pages, 3 figures, submitted to J. Opt. B: Quantum Semiclass. Opt. Proceedings of ICSSUR'0

Polarization-based Light-Atom Quantum Interface with an All-optical Trap

We describe the implementation of a system for studying light-matter interactions using an ensemble of $10^6$ cold rubidium 87 atoms, trapped in a single-beam optical dipole trap. In this configuration the elongated shape of the atomic cloud increases the strength of the collective light-atom coupling. Trapping all-optically allows for long storage times in a low decoherence environment. We are able to perform several thousands of measurements on one atomic ensemble with little destruction. We report results on paramagnetic Faraday rotations from a macroscopically polarized atomic ensemble. Our results confirm that strong light-atom coupling is achievable in this system which makes it attractive for single-pass quantum information protocols.Comment: 8 pages, 4 figure