31,439 research outputs found
Scale-invariant large nonlocality in polycrystalline graphene
The observation of large nonlocal resistances near the Dirac point in
graphene has been related to a variety of intrinsic Hall effects, where the
spin or valley degrees of freedom are controlled by symmetry breaking
mechanisms. Engineering strong spin or valley Hall signals on scalable graphene
devices could stimulate further practical developments of spin- and
valleytronics. Here we report on scale-invariant nonlocal transport in
large-scale chemical vapour deposition graphene under an applied external
magnetic field. Contrary to previously reported Zeeman spin Hall effect, our
results are explained by field-induced spin-filtered edge states whose
sensitivity to grain boundaries manifests in the nonlocal resistance. This
phenomenon, related to the emergence of the quantum Hall regime, persists up to
the millimeter scale, showing that polycrystalline morphology can be imprinted
in nonlocal transport. This suggests that topological Hall effects in
large-scale graphene materials are highly sensitive to the underlying
structural morphology, limiting practical realizations.Comment: Main paper (14 pages, 5 figures) and Supplementary information (8
pages, 8 figures
The Landscape of Academic Literature in Quantum Technologies
In this study, we investigated the academic literature on quantum
technologies (QT) using bibliometric tools. We used a set of 49,823 articles
obtained from the Web of Science (WoS) database using a search query
constructed through expert opinion. Analysis of this revealed that QT is deeply
rooted in physics, and the majority of the articles are published in physics
journals. Keyword analysis revealed that the literature could be clustered into
three distinct sets, which are (i) quantum communication/cryptography, (ii)
quantum computation, and (iii) physical realizations of quantum systems. We
performed a burst analysis that showed the emergence and fading away of certain
key concepts in the literature. This is followed by co-citation analysis on the
highly cited articles provided by the WoS, using these we devised a set of core
corpus of 34 publications. Comparing the most highly cited articles in this set
with respect to the initial set we found that there is a clear difference in
most cited subjects. Finally, we performed co-citation analyses on country and
organization levels to find the central nodes in the literature. Overall, the
analyses of the datasets allowed us to cluster the literature into three
distinct sets, construct the core corpus of the academic literature in QT, and
to identify the key players on country and organization levels, thus offering
insight into the current state of the field. Search queries and access to
figures are provided in the appendix.Comment: 32 pages, 10 figures, draft version of a working pape
Epistemic and Ontic Quantum Realities
Quantum theory has provoked intense discussions about its interpretation since its pioneer days. One of the few scientists who have been continuously engaged in this development from both physical and philosophical perspectives is Carl Friedrich von Weizsaecker. The questions he posed were and are inspiring for many, including the authors of this contribution. Weizsaecker developed Bohr's view of quantum theory as a theory of knowledge. We show that such an epistemic perspective can be consistently complemented by Einstein's ontically oriented position
Unreduced Dynamic Complexity: Towards the Unified Science of Intelligent Communication Networks and Software
Operation of autonomic communication networks with complicated user-oriented functions should be described as unreduced many-body interaction process. The latter gives rise to complex-dynamic behaviour including fractally structured hierarchy of chaotically changing realisations. We recall the main results of the universal science of complexity (http://cogprints.org/4471/) based on the unreduced interaction problem solution and its application to various real systems, from nanobiosystems (http://cogprints.org/4527/) and quantum devices to intelligent networks (http://cogprints.org/4114/) and emerging consciousness (http://cogprints.org/3857/). We concentrate then on applications to autonomic communication leading to fundamentally substantiated, exact science of intelligent communication and software. It aims at unification of the whole diversity of complex information system behaviour, similar to the conventional, "Newtonian" science order for sequential, regular models of system dynamics. Basic principles and first applications of the unified science of complex-dynamic communication networks and software are outlined to demonstrate its advantages and emerging practical perspectives
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