Paradigmatic States Research Articles

Generation of photonic tensor network states with circuit QED

We propose a circuit QED platform and protocol to generate microwave photonic tensor network states deterministically. We first show that using a microwave cavity as ancilla and a transmon qubit as emitter is a good platform to produce photonic matrix product states. The ancilla cavity combines a large controllable Hilbert space with a long coherence time, which we predict translates into a high number of entangled photons and states with a high bond dimension. Going beyond this paradigm, we then consider a natural generalization of this platform, in which several cavity-qubit pairs are coupled to form a chain. The photonic states thus produced feature a two-dimensional entanglement structure and can be interpreted as $\textit{radial plaquette}$ projected entangled pair states [Wei, Malz, and Cirac, Phys. Rev. Lett. 128, 010607 (2022)], which include many paradigmatic states, such as the broad class of isometric tensor network states, graph states, and string-net states.

Hidden racism and structures of power in the images of Ebola 2014

Epidemics are considered paradigmatic states of emergency and humanitarian scenarios. Thus, humanitarian conceptualizations are negotiable through the very practices appearing in this type of emergency.
 This paper aims to investigate this process in relation to the 2014 Ebola outbreak, an event that is considered a global threat and an intolerable humanitarian situation. We analyze how the definition of what can be understood (or not) as humanity was constructed through visual representations produced by social media. We will also discuss how the definition of humanity was negotiated through dimensions such as the spectrum of visibility, the distribution of agencies, the affections intended to provoke, and the imaginaries defined. This paper is based on an empirical semiotic analysis of hundreds of images from the 2014 Ebola epidemic and 15 focus groups and individual interviews, performed over a span of one year, discussing images from social media.

Dirac fermions and flat bands in the ideal kagome metal FeSn.

A kagome lattice of 3d transition metal ions is a versatile platform for correlated topological phases hosting symmetry-protected electronic excitations and magnetic ground states. However, the paradigmatic states of the idealized two-dimensional kagome lattice-Dirac fermions and flat bands-have not been simultaneously observed. Here, we use angle-resolved photoemission spectroscopy and de Haas-van Alphen quantum oscillations to reveal coexisting surface and bulk Dirac fermions as well as flat bands in the antiferromagnetic kagome metal FeSn, which has spatially decoupled kagome planes. Our band structure calculations and matrix element simulations demonstrate that the bulk Dirac bands arise from in-plane localized Fe-3d orbitals, and evidence that the coexisting Dirac surface state realizes a rare example of fully spin-polarized two-dimensional Dirac fermions due to spin-layer locking in FeSn. The prospect to harness these prototypical excitations in a kagome lattice is a frontier of great promise at the confluence of topology, magnetism and strongly correlated physics.

Stage image of fashion as the integrity of the aesthetic and cultural initiatives

The purpose of the article. Determine the culturological components of the formation of fashion activity as a scenic phenomenon. Methodology of the research is based on the analytical method in the study of artistic peculiarities of the development of visual culture; historical - in the reconstruction and rehabilitation of the socio-cultural field of reality and functions of art; culturological - for the complex definition of ideological and stylistic paradigms of transformations of figurative artifacts of culture. Scientific novelty. Fashion as the integrity of aesthetic and cultural preferences in the context of globalization processes of the late XX - early XXI centuries becomes an active actor in the alternative globalization movement. Together with the processes of universalization and actualization of cultural and historical potential, fashion is understood as a global practice of cultural creation. Fashion is interpreted as a form of human cultural activity; it generates the potential of a model business, a culture of everyday life, a spectacular culture, and the like. Conclusions. Fashion in the context of world culture is a certain cultural and historical anthropology that represents the integrity of the person, as well as fashionable innovations in the context of various forms of the form: genre, stylistic, which gives an opportunity to see the limits of human creativity, the limits of the fashionable embodiment. The fashion carries the image of a grotesque. Fashion is also a fundamental mechanism of cultural cultivation, the specificity of which is expressed in the constitution of the processes of form-building in culture. Thus, by itself the design of fashion, fashion, stage, openness to another, and at the same time the desire to be self-sufficient and beautiful space, this indicates that the fashion is opened in different contexts of cultural development, in particular in design, theater, advertising, cinema, virtual reality. All these contexts somehow give different paradigmatic states, images of all that living, juvenile organism of the society, which can be noted as a fashionable universe that correlates with the universe scenic.

Unifying neural-network quantum states and correlator product states via tensor networks

Correlator product states (CPS) are a powerful and very broad class of states for quantum lattice systems whose (unnormalised) amplitudes in a fixed basis can be sampled exactly and efficiently. They work by gluing together states of overlapping clusters of sites on the lattice, called correlators. Recently Carleo and Troyer (2017 Science 355 602) introduced a new type sampleable ansatz called neural-network quantum states (NQS) that are inspired by the restricted Boltzmann model used in machine learning. By employing the formalism of tensor networks we show that NQS are a special form of CPS with novel properties. Diagramatically a number of simple observations become transparent. Namely, that NQS are CPS built from extensively sized GHZ-form correlators making them uniquely unbiased geometrically. The appearance of GHZ correlators also relates NQS to canonical polyadic decompositions of tensors. Another immediate implication of the NQS equivalence to CPS is that we are able to formulate exact NQS representations for a wide range of paradigmatic states, including superpositions of weighed-graph states, the Laughlin state, toric code states, and the resonating valence bond state. These examples reveal the potential of using higher dimensional hidden units and a second hidden layer in NQS. The major outlook of this study is the elevation of NQS to correlator operators allowing them to enhance conventional well-established variational Monte Carlo approaches for strongly correlated fermions.

Irreducible forms of matrix product states: Theory and applications

The canonical form of Matrix Product States (MPS) and the associated fundamental theorem, which relates different MPS representations of a state, are the theoretical framework underlying many of the analytical results derived through MPS, such as the classification of symmetry-protected phases in one dimension. Yet, the canonical form is only defined for MPS without non-trivial periods and thus cannot fully capture paradigmatic states such as the antiferromagnet. Here, we introduce a new standard form for MPS, the irreducible form, which is defined for arbitrary MPS, including periodic states, and show that any tensor can be transformed into a tensor in irreducible form describing the same MPS. We then prove a fundamental theorem for MPS in irreducible form: If two tensors in irreducible form give rise to the same MPS, then they must be related by a similarity transform, together with a matrix of phases. We provide two applications of this result: an equivalence between the refinement properties of a state and the divisibility properties of its transfer matrix, and a more general characterisation of tensors that give rise to matrix product states with symmetries.

Losing traction and the art of slip-sliding away: Or, getting over education for sustainable development

ABSTRACTThis response problematizes Stefan Bengtsson's (2016) defense of education for sustainable development. He argues that sustainable development and education for sustainable development are not globalizing and hegemonic discourses, as some have claimed, and uses case-study analysis of Vietnamese policy documents to support his claims. He observes contestation and dissensus within these documents, and that, for him, is at odds with his conceptions of hegemony and paradigmatic status. He also suggests that this dissensus provides openings for opposition and resistance. I argue, on the contrary, that disagreement, dissent, anomalies, and counter-hegemonic forces have always been part of hegemonic struggles and paradigmatic states—and shifts. Bengtsson and I do agree about the importance of dissensus and resistance; however, important choices remain to be made about what concepts and contexts of dissensus are most educationally valuable. For example, I show that Bengtsson's Vietnamese policy data suggests that although dissensus exists, sustainable development and education for sustainable development have had little impact in generating counter-hegemonic discourse, resistance, anomalous responses, or creative alternatives in the environmental and social policy. Based on the data, sustainable development does not seem to have much traction. I argue that a useful approach would be to focus on understandings currently absent or underrepresented in contemporary education. Particularly important are the understandings required to think differently and to become different beings. Throughout, attention has been given to developing educational experiences that arise that shift the way learners carry themselves in the world, enact their etiquette, and broaden their ontological positioning, and commensurate understandings.

Sonine approximation for collisional moments of granular gases of inelastic rough spheres

We consider a dilute granular gas of hard spheres colliding inelastically with coefficients of normal and tangential restitution α and β, respectively. The basic quantities characterizing the distribution function f(v,ω) of linear (v) and angular (ω) velocities are the second-degree moments defining the translational (Ttr) and rotational (Trot) temperatures. The deviation of f from the Maxwellian distribution parameterized by Ttr and Trot can be measured by the cumulants associated with the fourth-degree velocity moments. The main objective of this paper is the evaluation of the collisional rates of change of these second- and fourth-degree moments by means of a Sonine approximation. The results are subsequently applied to the computation of the temperature ratio Trot/Ttr and the cumulants of two paradigmatic states: the homogeneous cooling state and the homogeneous steady state driven by a white-noise stochastic thermostat. It is found in both cases that the Maxwellian approximation for the temperature ratio does not deviate much from the Sonine prediction. On the other hand, non-Maxwellian properties measured by the cumulants cannot be ignored, especially in the homogeneous cooling state for medium and small roughness. In that state, moreover, the cumulant directly related to the translational velocity differs in the quasi-smooth limit β→−1 from that of pure smooth spheres (β=−1). This singular behavior is directly related to the unsteady character of the homogeneous cooling state and thus it is absent in the stochastic thermostat case.

Second thoughts on the prevalence of enhancement

In his review of an edited volume on ‘neuroenhancement’, Boris Quednow raises the question whether we really need a debate on a technology that will probably never materialise (Quednow, 2010). In philosophy, it is not uncommon to discuss hypothetical questions in the absence of concrete applications, for example whether sophisticated robots should be granted civil rights (Putnam, 1975). Such hypothetical discussions ideally help us to probe our intuitions and to refine our understanding of underlying assumptions. In this respect, I welcome the debate on cognitive enhancement, as it addresses relevant issues, such as the potential of neuroscientific interventions to alter personality, the role of proper functioning and performance in competitive societies and, ultimately, what constitutes a good life. Many of these issues are relevant whether these interventions are primarily used for purposes of clinical treatment or cognitive enhancement. However, there is a sense in which I welcome Quednow’s critical remarks: in the competition for media attention and research funding, the exaggeration of a trend might actually play an important function and bias individual and policy decisions. I share Quednow’s perception that the prevalence of enhancement is indeed overstated, though I am afraid that this misrepresentation is more frequent than his single case study suggests. For example, an influential paradigmatic paper states that the use of prescription stimulants ‘as study aids [y] might include as many as 16 per cent of the students on some campuses’ (Farah et al, 2004, p. 421). The authors of the original study merely asked for recreational use of a number of drugs in their survey with questions such as ‘have you ever used methylphenidate for fun?’ (Babcock and Byrne, 2000). A similar error involving this particular study can be found in many other papers on enhancement (see Schleim, 2010). Another paradigmatic paper that fuelled the public discussion in many countries stated that ‘on some campuses, up to 25 per cent of students had used them in the past year’, referring to prescription drugs used as study aids (Greely et al, 2008, p. 702). Although there was indeed such an extreme outlier – one in 119 – in the detailed study investigating stimulant consumption, the authors did not ask the students for the motives of their consumption other than that they be ‘nonmedical’ (McCabe et al, 2005). This leaves room for other motives than cognitive enhancement, such as having fun, experiencing a ‘high’ or losing weight. The figures of this study thus cannot be interpreted with regard to the prevalence of cognitive enhancement. Again, this error is widespread (see Schleim, 2010). Such an overestimation carries the risk to suggest that the drugs are safe and effective – for why should so many people otherwise use them? Responses

No Other Way Out: States and Revolutionary Movements, 1945–1991. By Jeff Goodwin. Cambridge: Cambridge University Press, 2001. 428p. $60.00 cloth, $23.00 paper.

“Do we need yet another comparative study of revolutions?” (p. 5; emphasis in original), Jeff Goodwin asks in this eagerly (and long) anticipated and important new book, which is destined to influence scholars in several disciplines and fields. The answer, as this volume makes abundantly clear, is “yes,” and few will be disappointed with this well-written, accessible, and compelling volume, the most nuanced and sophisticated argument yet for the state-centered (but, pace Goodwin, not structuralist; see p. 53) approach, and worthy heir to Theda Skocpol's (1979) still paradigmatic States and Social Revolutions. But therein lies the rub: Rather than the first book of the (putative) emergent fourth generation of scholars of revolution(s), this is likely the last of the third generation. Goodwin concedes he has “largely moved beyond” (p. xvi) the perspective he articulates here, and he, along with John Foran, is one of the most likely suspects to produce the next paradigmatic statement on revolutions. This, then, would seem the third generation's crowning glory; given the long gestation period and the prolific Goodwin's many and impressive contributions to matters revolutionary, this is almost more a legend than a book.

Syntagmatic and paradigmatic states in spoken word recognition

The process of spoken word recognition has frequently been characterized as a mapping of information through a multidimensional space, the dimensions of which correspond to time and acoustic-phonetic similarity. Within this framework, the speed and accuracy of spoken word recognition is a direct function of the ease of traversing a path through the space. The traversal of a path may be affected by at least two states of the space at any point in processing: The first, or syntagmatic, state refers to the history and future of the path. The syntagmatic states of a word correspond to its ‘‘probabilistic’’ phonotactics. The second, or paradigmatic, state refers to the degree of activation within the space at any point (or what has previously been referred to as ‘‘neighborhood activation’’). A connectionist instantiation will be presented of this framework that attempts to predict the speed and accuracy of spoken word recognition as function of syntagmatic and paradigmatic states. Also discussed is a number of empirical tests of the model that provide further insights into the roles of phonotactics and neighborhood structure in spoken word recognition. [Work supported by NIH Grant No. DC-00879-01 to the State University of New York at Buffalo.]