1,390 research outputs found
A history based logic for dynamic preference updates
History based models suggest a process-based approach to epistemic and temporal reasoning. In this work, we introduce preferences to history based models. Motivated by game theoretical observations, we discuss how preferences can dynamically be updated in history based models. Following, we consider arrow update logic and event calculus, and give history based models for these logics. This allows us to relate dynamic logics of history based models to a broader framework
Efficient optical quantum state engineering
We discuss a novel method of efficiently producing multi-photon states using
repeated spontaneous parametric downconversion. Specifically, by attempting
downconversion several times, we can pseudo-deterministically add photons to a
mode, producing various several-photon states. We discuss both expected
performance and experimental limitations.Comment: 4 pages, 4 figure
Security of high-dimensional quantum key distribution protocols using Franson interferometers
Franson interferometers are increasingly being proposed as a means of
securing high-dimensional energy-time entanglement-based quantum key
distribution (QKD) systems. Heuristic arguments have been proposed that purport
to demonstrate the security of these schemes. We show, however, that such
systems are vulnerable to attacks that localize the photons to several
temporally separate locations. This demonstrates that a single pair of Franson
interferometers is not a practical approach to securing high-dimensional
energy-time entanglement based QKD. This observations leads us to investigate
the security of modified Franson-based-protocols, where Alice and Bob have two
or more Franson interferometers. We show that such setups can improve the
sensitivity against attacks that localize the photons to multiple temporal
locations. While our results do not constituting a full security proof, they do
show that a single pair of Franson interferometers is not secure and that
multiple such interferometers could be a promising candidate for experimentally
realizable high-dimensional QKD.Comment: 14 pages (single column format
Nomenclature of structural and compositional characteristics of ordered microporous and mesoporous materials with inorganic hosts(IUPAC Recommendations 2001)
A system of terms applicable to ordered microporous and mesoporous materials is proposed, and rules for writing a standardized crystal chemical formula for such materials are presented. The recommendations are based both on common usage and on a systematic classification scheme. The nomenclature has been developed to encompass all inorganic materials with ordered, accessible pores with free diameters of less than 50 nm. The crystal chemical formula describes the chemical composition of both the guest species and the host, the structure of the host, the structure of the pore system, and the symmetry of the material. This formula can be simplified or expanded to suit the user's requirement
A feminist teacher’s account of her attempts to achieve the goals of feminist pedagogy
© 2017 Informa UK Limited, trading as Taylor & Francis Group. This paper aims to interrogate some of the processes and tensions I faced in establishing a feminist space in a higher education institution in the UK context. The students I worked with needed to develop an understanding of social justice concepts such as anti-discrimination and anti-oppression in order to progress from their undergraduate studies to a postgraduate professional qualification in social work. It was my contention that a feminist lens could support this understanding. The feminist space we established was informed by work in the field of feminist pedagogy, which supports the development of critical thinking that goes beyond the immediate learning context. Feminist pedagogy brings many rewards but also challenges and tensions, some of which I will explore in the paper. I will focus here on my efforts to establish and maintain this space, discussing what was achieved, and exploring the tensions involved when doing this in a neoliberal context, which as a depoliticised context, is a challenge to, and is challenged by, critical perspectives such as feminism
Detection-Loophole-Free Test of Quantum Nonlocality, and Applications
We present a source of entangled photons that violates a Bell inequality free
of the "fair-sampling" assumption, by over 7 standard deviations. This
violation is the first experiment with photons to close the detection loophole,
and we demonstrate enough "efficiency" overhead to eventually perform a fully
loophole-free test of local realism. The entanglement quality is verified by
maximally violating additional Bell tests, testing the upper limit of quantum
correlations. Finally, we use the source to generate secure private quantum
random numbers at rates over 4 orders of magnitude beyond previous experiments.Comment: Main text: 5 pages, 2 figures, 1 table. Supplementary Information: 7
pages, 2 figure
Efficient generation of single and entangled photons on a silicon photonic integrated chip
We present a protocol for generating on-demand, indistinguishable single
photons on a silicon photonic integrated chip. The source is a time-multiplexed
spontaneous parametric down-conversion element that allows optimization of
single-photon versus multiphoton emission while realizing high output rate and
indistinguishability. We minimize both the scaling of active elements and the
scaling of active element loss with multiplexing. We then discuss detection
strategies and data processing to further optimize the procedure. We simulate
an improvement in single-photon-generation efficiency over previous
time-multiplexing protocols, assuming existing fabrication capabilities. We
then apply this system to generate heralded Bell states. The generation
efficiency of both nonclassical states could be increased substantially with
improved fabrication procedures.Comment: 7 pages, 4 figure
The Septins Function in G1 Pathways that Influence the Pattern of Cell Growth in Budding Yeast
The septins are a conserved family of proteins that have been proposed to carry out diverse functions. In budding yeast, the septins become localized to the site of bud emergence in G1 but have not been thought to carry out important functions at this stage of the cell cycle. We show here that the septins function in redundant mechanisms that are required for formation of the bud neck and for the normal pattern of cell growth early in the cell cycle. The Shs1 septin shows strong genetic interactions with G1 cyclins and is directly phosphorylated by G1 cyclin-dependent kinases, consistent with a role in early cell cycle events. However, Shs1 phosphorylation site mutants do not show genetic interactions with the G1 cyclins or obvious defects early in the cell cycle. Rather, they cause an increased cell size and aberrant cell morphology that are dependent upon inhibitory phosphorylation of Cdk1 at the G2/M transition. Shs1 phosphorylation mutants also show defects in interaction with the Gin4 kinase, which associates with the septins during G2/M and plays a role in regulating inhibitory phosphorylation of Cdk1. Phosphorylation of Shs1 by G1 cyclin-dependent kinases plays a role in events that influence Cdk1 inhibitory phosphorylation
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