Indefinite Causal Order in a Quantum Switch

In quantum mechanics events can happen in no definite causal order: in practice this can be verified by measuring a causal witness, in the same way that an entanglement witness verifies entanglement. Indefinite causal order can be observed in a quantum switch, where two operations act in a quantum superposition of the two possible orders. Here we realise a photonic quantum switch, where polarisation coherently controls the order of two operations, $\hat{A}$ and $\hat{B}$, on the transverse spatial mode of the photons. Our setup avoids the limitations of earlier implementations: the operations cannot be distinguished by spatial or temporal position. We show that our quantum switch has no definite causal order, by constructing a causal witness and measuring its value to be 18 standard deviations beyond the definite-order bound

Archaeological practices, knowledge work and digitalisation

Defining what constitute archaeological practices is a prerequisite for understanding where and how archaeological and archaeologically relevant information and knowledge are made, what counts as archaeological information, and where the limits are situated. The aim of this position paper, developed as a part of the COST action Archaeological practices and knowledge work in the digital environment (www.arkwork.eu), is to highlight the need for at least a relative consensus on the extents of archaeological practices in order to be able to understand and develop archaeological practices and knowledge work in the contemporary digital context. The text discusses approaches to study archaeological practices and knowledge work including Nicolini’s notions of zooming in and zooming out, and proposes that a distinction between archaeological and archaeology-related practices could provide a way to negotiate the ‘archaeologicality’ of diverse practices

Video recording true single-photon double-slit interference

As normally used, no commercially available camera has a low-enough dark noise to directly produce video recordings of double-slit interference at the photon-by-photon level, because readout noise significantly contaminates or overwhelms the signal. In this work, noise levels are significantly reduced by turning on the camera only when the presence of a photon has been heralded by the arrival, at an independent detector, of a time-correlated photon produced via parametric down-conversion. This triggering scheme provides the improvement required for direct video imaging of Young's double-slit experiment with single photons, allowing clarified versions of this foundational demonstration. Further, we introduce variations on this experiment aimed at promoting discussion of the role spatial coherence plays in such a measurement. We also emphasize complementary aspects of single-photon measurement, where imaging yields (transverse) position information, while diffraction yields the transverse momentum, and highlight the roles of transverse position and momentum correlations between down-converted photons, including examples of "ghost" imaging and diffraction. The videos can be accessed at http://sun.iwu.edu/~gspaldin/SinglePhotonVideos.html online.Comment: 7 pages, 8 figure

Childhood and the politics of scale: Descaling children's geographies?

This is the post-print version of the final published paper that is available from the link below. Copyright @ 2008 SAGE Publications.The past decade has witnessed a resurgence of interest in the geographies of children's lives, and particularly in engaging the voices and activities of young people in geographical research. Much of this growing body of scholarship is characterized by a very parochial locus of interest — the neighbourhood, playground, shopping mall or journey to school. In this paper I explore some of the roots of children's geographies' preoccupation with the micro-scale and argue that it limits the relevance of research, both politically and to other areas of geography. In order to widen the scope of children's geographies, some scholars have engaged with developments in the theorization of scale. I present these arguments but also point to their limitations. As an alternative, I propose that the notion of a flat ontology might help overcome some difficulties around scalar thinking, and provide a useful means of conceptualizing sociospatiality in material and non-hierarchical terms. Bringing together flat ontology and work in children's geographies on embodied subjectivity, I argue that it is important to examine the nature and limits of children's spaces of perception and action. While these spaces are not simply `local', they seldom afford children opportunities to comment on, or intervene in, the events, processes and decisions that shape their own lives. The implications for the substance and method of children's geographies and for geographical work on scale are considered

Repair Matters

Repair has visibly come to the fore in recent academic and policy debates, to the point that ‘repair studies’ is now emerging as a novel focus of research. Through the lens of repair, scholars with diverse backgrounds are coming together to rethink our relationships with the human-made matters, tools and objects that are the material mesh in which organisational life takes place as a political question. This special issue is interested to map the ways that repair can contribute to organisational models alternative to those centered around growth. In order to explore the politics of repair in the context of organization studies, the papers gathered here investigate issues such as: repair as a specific kind of care and socially reproductive labour; repair as a direct intervention into the cornerstones of capitalist economy, such as exchange versus use value, division of work and property relations; repair of infrastructures and their relation with the broader environment; and finally repair as the reflective practice of fixing the organizational systems and institutional habits in which we dwell. What emerges from the diversity of experiences surveyed in this issue is that repair manifests itself as both a regime of practice and counter-conduct that demand an active and persistent engagement of practitioners with the systemic contradictions and power struggles shaping our material world

The Armenian Üsküdar amid a conditional plurality

This dissertation is devoted to exploring Armenian Üsküdar (an Anatolian side municipality of Istanbul) and its surroundings within the lenses of “conviviality” as conceptualized by Freitag (2014). Armenian neighborhoods in Üsküdar had all its relevance within the Ottoman rule in Constantinople, and throughout the Republican period, gradually dissolved to the extent that the notion of Üsküdar Armenians make little to no sense today. In this dissertation, the Armenian neighborhoods with its public spaces: streets, theatres, music halls, taverns; and community spaces: churches and schools will be reconstructed. It will demonstrate how Armenian Üsküdar spatially integrated into the larger geography. Although divided by orchards, large roads and cemeteries, this study will also illustrate how Üsküdar Armenian neighborhoods seem to have been compact, as if isolated from the rest. The spatial, political and social parameters that contributed to the Armenian’s dominant position will be contextualized in the three neighborhoods: Yeni Mahalle, Selamsız and İcadiye. Moreover, I will demonstrate how the center of gravity in the Armenian Üsküdar had shifted initially from Yeni Mahalle to Selamsız, and then in the late 19th century to İcadiye. By doing so, this study traces spatial imprints of the transformation of the power structure within the Armenian community, a major shift of the power from traditional aristocratic elite with ties to the Ottoman government, solidifying in Selamsız; to the modern elite gradually but powerfully flourishing in İcadiye

London in space and time: Peter Ackroyd and Will Self

Copyright @ 2013 the author. This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Unported License.This paper explores the treatment of London by two authors who are profoundly influenced by the concept of the power of place and the nature of urban space. The works of Peter Ackroyd, whose writings embody, according to Onega (1997, p. 208) “[a] yearning for mythical closure” where London is “a mystic centre of power” – spiritual, transhistorical and cultural – are considered alongside those of Will Self, who explores the city’s psychogeography as primarily a political, economic and cultural artefact. The paper draws on original interviews undertaken by the author with Ackroyd and Self. Both authors’ works are available for literary study during the 16-19 phase in the UK, and this paper explores how personal delineations of the urban environment are shaped by space and language. It goes on to consider how authors’ and students’ personal understandings of space and place can be used as pedagogical and theoretical lenses to “read” the city in the 16-19 literature classroom

Editorial: Craft and the Handmade: Making the intangible visible

In November 2014, the Department of Fashion and Textiles at the University of Huddersfield hosted the conference Transition: Re-thinking Textiles and Surfaces. The conference sought to scrutinize current and future developments in textile research and its applications within the wider context of the creative industries. With keynote presentations from Professor Becky Earley, Professor Jane Harris, Dr Subramanian Senthilkannan Muthu, publisher David Shah and Trend Union forecaster Philip Fimmano, this two day event brought together a myriad of theoretical perspectives and material approaches through four distinct tracks: Science and Technology, Sustainable Futures, Craft and the Handmade and Enterprise/Industry/Business. This guest edited issue of Craft Research focuses on Craft and the Handmade and features articles that were first delivered as papers within this track

Gravitational lensing: a unique probe of dark matter and dark energy

I review the development of gravitational lensing as a powerful tool of the observational cosmologist. After the historic eclipse expedition organized by Arthur Eddington and Frank Dyson, the subject lay observationally dormant for 60 years. However, subsequent progress has been astonishingly rapid, especially in the past decade, so that gravitational lensing now holds the key to unravelling the two most profound mysteries of our Universe—the nature and distribution of dark matter, and the origin of the puzzling cosmic acceleration first identified in the late 1990s. In this non-specialist review, I focus on the unusual history and achievements of gravitational lensing and its future observational prospects