97 research outputs found
Selective Area Grown Semiconductor-Superconductor Hybrids: A Basis for Topological Networks
We introduce selective area grown hybrid InAs/Al nanowires based on molecular
beam epitaxy, allowing arbitrary semiconductor-superconductor networks
containing loops and branches. Transport reveals a hard induced gap and
unpoisoned 2e-periodic Coulomb blockade, with temperature dependent 1e features
in agreement with theory. Coulomb peak spacing in parallel magnetic field
displays overshoot, indicating an oscillating discrete near-zero subgap state
consistent with device length. Finally, we investigate a loop network, finding
strong spin-orbit coupling and a coherence length of several microns. These
results demonstrate the potential of this platform for scalable topological
networks among other applications.Comment: NBI QDEV 201
Type-based allocation analysis for co-recursion in lazy functional languages
This paper presents a novel type-and-effect analysis for pre-dicting upper-bounds on memory allocation costs for co-recursive def-initions in a simple lazily-evaluated functional language. We show thesoundness of this system against an instrumented variant of Launch-bury’s semantics for lazy evaluation which serves as a formal cost model.Our soundness proof requires an intermediate semantics employing indi-rections. Our proof of correspondence between these semantics that weprovide is thus a crucial part of this work.The analysis has been implemented as an automatic inference system.We demonstrate its effectiveness using several example programs thatpreviously could not be automatically analysed.Postprin
Transforming data by calculation
Thispaperaddressesthefoundationsofdata-modeltransformation.A catalog of data mappings is presented which includes abstraction and representa- tion relations and associated constraints. These are justified in an algebraic style via the pointfree-transform, a technique whereby predicates are lifted to binary relation terms (of the algebra of programming) in a two-level style encompassing both data and operations. This approach to data calculation, which also includes transformation of recursive data models into “flat” database schemes, is offered as alternative to standard database design from abstract models. The calculus is also used to establish a link between the proposed transformational style and bidi- rectional lenses developed in the context of the classical view-update problem.Fundação para a Ciência e a Tecnologia (FCT
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