A Universal Theory of Spin Squeezing

We provide extensive numerical and analytic evidence for the following conjecture: Any Hamiltonian exhibiting finite temperature, easy-plane ferromagnetism (XY order) can be used to generate scalable spin squeezing, and thus to perform quantum-enhanced sensing. Our conjecture is guided by a deep connection between the quantum Fisher information of pure states and the spontaneous breaking of a continuous symmetry. We demonstrate that spin-squeezing exhibits a phase diagram with a sharp transition between scalable squeezing and non-squeezing. This transition coincides with the equilibrium phase boundary for XY order at a finite temperature. In the scalable squeezing phase, we predict a sensitivity scaling as $N^{-7/10}$, between the standard quantum limit, $N^{-1/2}$, and that achieved in all-to-all coupled easy-plane spin models, $N^{-5/6}$. Our results provide fundamental insight into the landscape of Hamiltonians that can be used to generate metrologically useful quantum states.Comment: 6 pages, 3 figures + 12 pages, 6 figure

Integrating research using animal-borne telemetry with the needs of conservation management

Animal-borne telemetry has revolutionized our ability to study animal movement, species physiology, demography and social structures, changing environments and the threats that animals are experiencing. While there will always be a need for basic ecological research and discovery, the current conservation crisis demands we look more pragmatically at the data required to make informed management decisions. Here, we define a framework that distinguishes how research using animal telemetry devices can influence conservation. We then discuss two critical questions which aim to directly connect telemetry-derived data to applied conservation decision-making: (i) Would my choice of action change if I had more data? (ii) Is the expected gain worth the money and time required to collect more data? Policy implications. To answer questions about integrating telemetry-derived data with applied conservation, we suggest the use of value of information analysis to quantitatively assess the return-on-investment of animal telemetry-derived data for conservation decision-making

Scalable spin squeezing in a dipolar Rydberg atom array

The standard quantum limit bounds the precision of measurements that can be achieved by ensembles of uncorrelated particles. Fundamentally, this limit arises from the non-commuting nature of quantum mechanics, leading to the presence of fluctuations often referred to as quantum projection noise. Quantum metrology relies on the use of non-classical states of many-body systems in order to enhance the precision of measurements beyond the standard quantum limit. To do so, one can reshape the quantum projection noise -- a strategy known as squeezing. In the context of many-body spin systems, one typically utilizes all-to-all interactions (e.g. the one-axis twisting model) between the constituents to generate the structured entanglement characteristic of spin squeezing. Motivated by recent theoretical work, here we explore the prediction that short-range interactions -- and in particular, the two-dimensional dipolar XY model -- can also enable the realization of scalable spin squeezing. Working with a dipolar Rydberg quantum simulator of up to 100 atoms, we demonstrate that quench dynamics from a polarized initial state lead to spin squeezing that improves with increasing system size up to a maximum of -3.5 dB (prior to correcting for detection errors, or approximately -5 dB after correction). Finally, we present two independent refinements: first, using a multistep spin-squeezing protocol allows us to further enhance the squeezing by approximately 1 dB, and second, leveraging Floquet engineering to realize Heisenberg interactions, we demonstrate the ability to extend the lifetime of the squeezed state by freezing its dynamics.Comment: 12 pages, 10 figure

Preference versus performance: Investigating the dissociation between objective measures and subjective ratings of usability for schematic metro maps and intuitive theories of design

Three experiments are reported in which objective measures and subjective ratings of schematic metro map usability were investigated. Experiment 1 used a within-subjects design to compare octolinear and curvilinear Paris Metro maps. This replicated and extended Roberts et al. (2013); the curvilinear map was associated with faster journey planning times, and yet preference between the two was unrelated to this measure. In Experiment 2, nine matched versions of the London Underground map were rated for usability and attractiveness, and a clear octolinear bias was displayed. It was also possible to identify individuals who held a simplicity theory of effective design, versus an octolinearity theory. Experiment 3 investigated the relationship between usability ratings and journey planning times for three Berlin network maps, all optimized for simplicity of line trajectories. No differences in times were found, and yet usability ratings after experience at using the maps differed significantly, in line with the findings for the London designs in Experiment 2. Overall, the dissociation between objective measures of performance and subjective ratings of usability is robust, and appears to reflect expectations and prejudices concerning effective design. The octolinearity as a gold standard conjecture for achieving optimum usability continues to be refuted

Reciprocal Relations Between Emotional Self-Efficacy Beliefs and Ego-Resiliency Across Time

The present study examined the longitudinal relations of adolescents' self-reported ego-resiliency to their emotional self-efficacy beliefs in expressing positive emotions and in managing negative emotions as they moved into early adulthood. Participants were 239 females and 211 males with a mean age of 17 years (SD = .80) at T1, 19 years (SD = .80) at T2, 21 years (SD = .82) at T3, and 25 years (SD = .80) at T4. A four-wave cross-lagged regression model and mediational analyses were used. In a panel structural equation model controlling for the stability of the constructs, reciprocal relationships across time were found between ego-resiliency and emotional self-efficacy beliefs related to the expression of positive emotions and to the management of negative emotions. Moreover, the relation between ego-resiliency assessed at T1 and T3, and ego-resiliency assessed at T2 and T4, was mediated through emotional self-efficacy beliefs (at T2 and T3, respectively), and vice versa. The posited conceptual model accounted for a significant portion of variance in ego-resiliency and has implications for understanding the development of ego-resiliency

Evaluation of MPA designs that protect highly mobile megafauna now and under climate change scenarios

Marine protected area (MPA) designs, including large-scale MPAs (LSMPAs; \u3e150,000 km2), mobile MPAs (fluid spatiotemporal boundaries), and MPA networks, may offer different benefits to species and could enhance protection by encompassing spatiotemporal scales of animal movement. We sought to understand how well LSMPAs could benefit nine highly-mobile marine species in the tropics now and into the future by: 1) evaluating current range overlap within a LSMPA; 2) evaluating range overlap under climate change projections; and 3) evaluating how well theoretical MPA designs benefit these nine species. We focused on Palmyra Atoll and Kingman Reef, a 2000 km2 area within the 1.2 million km2 U.S. Pacific Remote Islands Marine National Monument (PRIMNM) that contains marine megafauna (reef and pelagic fishes; sea turtles; seabirds; cetaceans) reflecting different behaviors and habitat use. Our approach is useful for evaluating the effectiveness of the Palmyra-Kingman MPA and PRIMNM in protecting these species, and tropical LSMPAs in general, and for informing future MPA design. Stationary MPAs provided protection at varying scales. Reef manta rays (Mobula alfredi), grey reef sharks (Carcharhinus amblyrhynchos), green sea turtles (Chelonia mydas), and bottlenose dolphins (Tursiops truncatus) had overall small ranges (\u3c100 km from Palmyra-Kingman) and could benefit from stationary MPAs that contained heterogenous reef habitats. Yellowfin tuna (Thunnus albacares), sooty terns (Onychoprion fuscatus), red-footed boobies (Sula sula), great frigatebirds (Fregata minor), and melon-headed whales (Peponocephala electra) navigated complex oceanographic processes and may benefit most from mobile MPAs that shift with features including thermal fronts, cyclic regions of elevated productivity, and eddies, if relationships with these features are established and predictable. All species had capacity to travel to nearby reef systems, illustrating potential benefits of MPA networks and protected corridors. Suitable habitats will likely contract for all species as warm water expands under climate change scenarios (species habitats were predicted to decrease by 4–49% at Palmyra-Kingman) and MPAs may not protect suitable habitats into the future. Species habitat requirements and movement ecologies are critical aspects of marine spatial planning, especially with respect to dynamic ocean processes and a changing climate