658,066 research outputs found
Designing colloidal ground state patterns using short-range isotropic interactions
DNA-coated colloids are a popular model system for self-assembly through
tunable interactions. The DNA-encoded linkages between particles theoretically
allow for very high specificity, but generally no directionality or long-range
interactions. We introduce a two-dimensional lattice model for particles of
many different types with short-range isotropic interactions that are pairwise
specific. For this class of models, we address the fundamental question whether
it is possible to reliably design the interactions so that the ground state is
unique and corresponds to a given crystal structure. First, we determine lower
limits for the interaction range between particles, depending on the complexity
of the desired pattern and the underlying lattice. Then, we introduce a
`recipe' for determining the pairwise interactions that exactly satisfies this
minimum criterion, and we show that it is sufficient to uniquely determine the
ground state for a large class of crystal structures. Finally, we verify these
results using Monte Carlo simulations.Comment: 19 pages, 7 figure
Designing computer-mediated epistemic interactions
International audienceWhilst certain types of interactions between learners are potential vehicles for conceptual change, favouring production of such interactions in computer-mediated communication situations remains a difficult problem. We describe the CONNECT task sequence and interface for collaborative text writing, whose design aims to promote epistemic interactions involving argumentation and explanation with respect to fundamental domain concepts. Our approach involves pairing students according to semantic distance between their individual texts, encouraging expression of opinions on ideas in those texts, giving appropriate instructions on discussions, and partly structuring interactions. Within an iterative design approach, we present the results of a study in which students were asked to collaboratively write texts across the net on the interpretation of a sound phenomenon in physics. The interactions produced contained a high amount of explanation and argumentation, although communication management remained problematic
Designing Kerr interactions using multiple superconducting qubit types in a single circuit
The engineering of Kerr interactions has great potential for quantum
information processing applications in multipartite quantum systems and for
investigation of many-body physics in a complex cavity-qubit network. We study
how coupling multiple different types of superconducting qubits to the same
cavity modes can be used to modify the self- and cross-Kerr effects acting on
the cavities and demonstrate that this type of architecture could be of
significant benefit for quantum technologies.
Using both analytical perturbation theory results and numerical simulations,
we first show that coupling two superconducting qubits with opposite
anharmonicities to a single cavity enables the effective self-Kerr interaction
to be diminished, while retaining the number splitting effect that enables
control and measurement of the cavity field. We demonstrate that this reduction
of the self-Kerr effect can maintain the fidelity of coherent states and
generalised Schr\"{o}dinger cat states for much longer than typical coherence
times in realistic devices. Next, we find that the cross-Kerr interaction
between two cavities can be modified by coupling them both to the same pair of
qubit devices. When one of the qubits is tunable in frequency, the strength of
entangling interactions between the cavities can be varied on demand, forming
the basis for logic operations on the two modes. Finally, we discuss the
feasibility of producing an array of cavities and qubits where intermediary and
on-site qubits can tune the strength of self- and cross-Kerr interactions
across the whole system. This architecture could provide a way to engineer
interesting many-body Hamiltonians and a useful platform for quantum simulation
in circuit quantum electrodynamics
“No powers, man!”: A student perspective on designing university smart building interactions
Smart buildings offer an opportunity for better performance and enhanced experience by contextualising services and interactions to the needs and practices of occupants. Yet, this vision is limited by established approaches to building management, delivered top-down through professional facilities management teams, opening up an interaction-gap between occupants and the spaces they inhabit. To address the challenge of how smart buildings might be more inclusively managed, we present the results of a qualitative study with student occupants of a smart building, with design workshops including building walks and speculative futuring. We develop new understandings of how student occupants conceptualise and evaluate spaces as they experience them, and of how building management practices might evolve with new sociotechnical systems that better leverage occupant agency. Our findings point to important directions for HCI research in this nascent area, including the need for HBI (Human-Building Interaction) design to challenge entrenched roles in building management
Designing for Cross-Device Interactions
Driven by technological advancements, we now own and operate an ever-growing number of digital devices, leading to an increased amount of digital data we produce, use, and maintain. However, while there is a substantial increase in computing power and availability of devices and data, many tasks we conduct with our devices are not well connected across multiple devices. We conduct our tasks sequentially instead of in parallel, while collaborative work across multiple devices is cumbersome to set up or simply not possible. To address these limitations, this thesis is concerned with cross-device computing. In particular it aims to conceptualise, prototype, and study interactions in cross-device computing. This thesis contributes to the field of Human-Computer Interaction (HCI)—and more specifically to the area of cross-device computing—in three ways: first, this work conceptualises previous work through a taxonomy of cross-device computing resulting in an in-depth understanding of the field, that identifies underexplored research areas, enabling the transfer of key insights into the design of interaction techniques. Second, three case studies were conducted that show how cross-device interactions can support curation work as well as augment users’ existing devices for individual and collaborative work. These case studies incorporate novel interaction techniques for supporting cross-device work. Third, through studying cross-device interactions and group collaboration, this thesis provides insights into how researchers can understand and evaluate multi- and cross-device interactions for individual and collaborative work. We provide a visualization and querying tool that facilitates interaction analysis of spatial measures and video recordings to facilitate such evaluations of cross-device work. Overall, the work in this thesis advances the field of cross-device computing with its taxonomy guiding research directions, novel interaction techniques and case studies demonstrating cross-device interactions for curation, and insights into and tools for effective evaluation of cross-device systems
Designing friends
Embodied Conversational Agents are virtual humans that can interact with humans using verbal and non-verbal forms of communication. In most cases, they have been designed for short interactions. This paper asks the question how one would start to design synthetic characters that can become your friends. We look at insights from social psychology and propose a methodology for designing friends
Direct Evidence for Dominant Bond-directional Interactions in a Honeycomb Lattice Iridate Na2IrO3
Heisenberg interactions are ubiquitous in magnetic materials and have been
prevailing in modeling and designing quantum magnets. Bond-directional
interactions offer a novel alternative to Heisenberg exchange and provide the
building blocks of the Kitaev model, which has a quantum spin liquid (QSL) as
its exact ground state. Honeycomb iridates, A2IrO3 (A=Na,Li), offer potential
realizations of the Kitaev model, and their reported magnetic behaviors may be
interpreted within the Kitaev framework. However, the extent of their relevance
to the Kitaev model remains unclear, as evidence for bond-directional
interactions remains indirect or conjectural. Here, we present direct evidence
for dominant bond-directional interactions in antiferromagnetic Na2IrO3 and
show that they lead to strong magnetic frustration. Diffuse magnetic x-ray
scattering reveals broken spin-rotational symmetry even above Neel temperature,
with the three spin components exhibiting nano-scale correlations along
distinct crystallographic directions. This spin-space and real-space
entanglement directly manifests the bond-directional interactions, provides the
missing link to Kitaev physics in honeycomb iridates, and establishes a new
design strategy toward frustrated magnetism.Comment: Nature Physics, accepted (2015
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