Effective three-body interactions in triangular optical lattices

We demonstrate that a triangular optical lattice of two atomic species, bosonic or fermionic, can be employed to generate a variety of novel spin-1/2 Hamiltonians. These include effective three-spin interactions resulting from the possibility of atoms tunneling along two different paths. Such interactions can be employed to simulate particular one or two dimensional physical systems with ground states that possess a rich structure and undergo a variety of quantum phase transitions. In addition, tunneling can be activated by employing Raman transitions, thus creating an effective Hamiltonian that does not preserve the number of atoms of each species. In the presence of external electromagnetic fields, resulting in complex tunneling couplings, we obtain effective Hamiltonians that break chiral symmetry. The ground states of these Hamiltonians can be used for the physical implementation of geometrical or topological objects.Comment: 10 pages, 5 figures, REVTEX. Experimental implementation elaborated, brief study of ground states give

Loops and Strings in a Superconducting Lattice Gauge Simulator

We propose an architecture for an analog quantum simulator of electromagnetism in 2+1 dimensions, based on an array of superconducting fluxonium devices. The encoding is in the integer (spin-1 representation of the quantum link model formulation of compact U(1) lattice gauge theory. We show how to engineer Gauss' law via an ancilla mediated gadget construction, and how to tune between the strongly coupled and intermediately coupled regimes. The witnesses to the existence of the predicted confining phase of the model are provided by nonlocal order parameters from Wilson loops and disorder parameters from 't Hooft strings. We show how to construct such operators in this model and how to measure them nondestructively via dispersive coupling of the fluxonium islands to a microwave cavity mode. Numerical evidence is found for the existence of the confined phase in the ground state of the simulation Hamiltonian on a ladder geometry.Comment: 17 pages, 5 figures. Published versio

'There is no heritage in Qatar': Orientalism, colonialism and other problematic histories

This article discusses the construction of Qatari heritage in the context of pre-conceived ideas of ‘cultural heritage’ predominant in the global and regional spheres that operate in this country. It considers the location of Qatar within Middle Eastern heritage discourses and debates, and identifies productive similarities as well as unique avenues for further discussion. The authors identify the challenge of formulating methodologies that are able to recognize, accommodate, encompass and reflect local heritage dialogues and practices that exist in Qatar, which may aid in further researching the wider Arabian Peninsula, its histories and heritages

Recipes for computing radiation from a Kerr black hole using Generalized Sasaki-Nakamura formalism: I. Homogeneous solutions

Central to black hole perturbation theory calculations is the Teukolsky equation that governs the propagation and the generation of radiation emitted by Kerr black holes. However, it is plagued by a long-ranged potential associated to the perturbation equation and hence a direct numerical integration of the equation is challenging. Sasaki and Nakamura devised a formulation that transforms the equation into a new equation that is free from the issue for the case of out-going gravitational radiation. The formulation was later generalized by Hughes to work for any type of radiation. In this work, we revamp the Generalized Sasaki-Nakamura (GSN) formalism and explicitly show the transformations that convert solutions between the Teukolsky and the GSN formalism for both in-going and out-going radiation of scalar, electromagnetic and gravitational type. We derive all necessary ingredients for the GSN formalism to be used in numerical computations. In particular, we describe a new numerical implementation of the formalism, GeneralizedSasakiNakamura.jl, that computes homogeneous solutions to both perturbation equation in the Teukolsky and the GSN formalism. The code works well at low frequencies and is even better at high frequencies by leveraging the fact that black holes are highly permeable to waves at high frequencies. This work lays the foundation for an efficient scheme to compute gravitational radiation from Kerr black holes and an alternative way to compute quasi-normal modes of Kerr black holes.Comment: 31 pages, 12 figure

Sketch-a-park Study of the usability of diagrams for participatory sketching

Children’s view in participation currently gaining popularity (CABE Space and CABE Education, 2004) along with digital tools of participation based on design exploration currently known as Digital Participatory Platforms (DPPs) (Falco and Kleinhans, 2018), (Gün et al., 2020). Space Syntax Theory (SST) offers a well-proven human-centred analytic framework with applications for public engagement via digital twins (Dembski et al., 2019). Yet, as some authors argue (Baeck and Saunders, 2015), (Dembski et al., 2020), more needs to be done to improve the experiential side of these systems and empower citizens and children, in particular, to carry out their designs within these events using what is. We argue that using diagrammatic sketching as the basis of DPPs is particularly suited for SST since most SS models work out abstractions of urban morphology which can be drawn using simple diagrammatic sketches. However, this type of drawing may prove too abstract for participants and questions remain open regarding the usability of this type of drawings in a participatory environment. It is yet to be proven whether general members of the public, in particular young kids, can engage with diagrammatic sketches and what influence digital environments have on this engagement. To address these questions, we carried out two pilot studies with participants aged 10 to 11-year-old where we asked them to carry out drawings of urban proposals with different levels of information regarding diagrammatic drawings. Tests were repeated with different groups making paper drawings as well as using a bespoke digital tool at different stages of the drawing. We develop an analytic framework for drawings and carry out a comparative study of the material produced. Results from the experiment suggest that 10- to 11-year-old can easily understand the abstraction behind diagrammatic sketches and adopt this technique as a form of expression. We observe that this happens more markedly when using digital tools. This suggests diagrammatic sketches have the potential to be deployed as part of a SS driven participatory tool

DRAWSCAPES: Study of the effectiveness of online diagrammatic sketching in participatory design

The increased user-friendliness of Space Syntax (SS) packages and their improved compatibility with popular 3D modelling software has pushed the use of Space Syntax Theory (SST) into the professional realm, making it approachable, not just by dedicated researchers, but also to an increasing number of practitioners. We argue that the applicability of SST can even go further if we use sketching as a form of interaction with the software, potentially opening up its use to general members of the public as part of a wider participatory process. We present a study that tries to understand whether the diagrams required for this form of engagement are easy to produce by non-professionals and once they are produced, see whether they have an impact on the planning process. We propose an experiment using an online design tool that allows participants to make drawings of urban proposals by drafting simple diagrams, beginning with connective paths followed by urban blocks using thicker versions of the same pen tool. We develop bespoke analytic methods to extract general patterns emerging from data, identify trends across different user groups, and study user interaction, design quality and user engagement. We take the expansion of UCL East as a case study and test our tool with several participant groups from the general staff and student population as well as external design professionals. Some of these professionals carry out the exercise after reviewing the design from UCL members. We obtained 700 drawings from 400 participants and carry out comparative studies across groups. The study concludes that general members of the public can understand the type of drawing exercise requested and produce designs of an adequate standard. We can also see that planners and architects observe positively the information coming from general members of the public and are willing to incorporate it into their designs

Sketching maps Comparison between digital diagrammatic sketches of urban connectivity and actual maps of landscape fabric

Digital Participatory Platforms (DPPs) are tools allowing general members of the public to express themselves through design actions. This field is rapidly expanding and has the potential to democratize SS theory, making it visible and relevant to many. Tools that allow participants to develop simple diagrams of urban form can be of help since these types of drawings are easy to make and relate directly to some of the abstractions behind SS theory. However, even if we general members of the public can develop these drawings, the relation between these types of drawings and the reality they may intend to represent has not been mapped sp far. To address this issue we propose an experiment where we compare 200 drawings produced by professionals as part of a participatory process with real scale maps of London parks. We develop an analytic method for the lines of these two datasets using geometric feature extraction and dimensionality reduction representation in a t-SNE scatter graph. Results indicate that, for some types of landscapes, the algorithm effectively matches sketches and map morphologies. In other cases, the geometries of sketches and maps of some landscapes are inherently different since designers tend to develop “cartoons” of their designs, forcing curvature of items or forgetting small details which end up being added into the design in later stages. This would suggest the need to develop sophisticated layers of detail in addition to digital tools if they are to adequately translate between a syntactic approach to design and real-life map results

Pengaruh Kinerja Hutang Terhadap Nilai Perusahaan Pada Perusahaan Pertambangan Batubara Yang Terdaftar Di BEI Periode 2010-2013

The primary goal of the company is to maximize firm value. Firm value is investor perceptionof the company's success rate, it is often associated with stock prices. This research aim to examine the effect of leverage towards the value of the company in the coal mining companies which listed on the Indonesia Stock Exchange with periods 2010-2011. The hypothesis was leverage has negative effect on firm value. This research uses secondary data, of the coal mining companies which listed on BEI with periods 2010-2013. Research sample of 15 companies, where the method used is purposive sampling is a sampling method that takes an object with the specified criteria. Leverage are measured using Debt to Equity Ratio (DER) and Debt to Asset Ratio (DAR). Meanwhile, firm value is measured using Price Earning Ratio (PER). Analysis of the data used to analyze the factor that affect firm value is simple linier regression analysis and hypothesis test used the t-statistic for testing the partial regression coeffiecient at level of significant 5%. The results of this research finds leverage (DER) has negative significant effect on firm value (PER) with predictive ability is 6,8% and it shown by R square, and leverage (DAR) has negative significant effect on firm value (PER) with predictive ability is 7,2% and it shown by R square

Engineering entanglement for metrology with rotating matter waves

Entangled states of rotating, trapped ultracold bosons form a very promising scenario for quantum metrology. In order to employ such states for metrology, it is vital to understand their detailed form and the enhanced accuracy with which they could measure phase, in this case generated through rotation. In this work, we study the rotation of ultracold bosons in an asymmetric trapping potential beyond the lowest Landau level (LLL) approximation. We demonstrate that while the LLL can identify reasonably the critical frequency for a quantum phase transition and entangled state generation, it is vital to go beyond the LLL to identify the details of the state and quantify the quantum Fisher information (which bounds the accuracy of the phase measurement). We thus identify a new parameter regime for useful entangled state generation, amenable to experimental investigation