2,052 research outputs found
Nonclassicality filters and quasiprobabilities
Necessary and sufficient conditions for the nonclassicality of bosonic
quantum states are formulated by introducing nonclassicality filters and
nonclassicality quasiprobability distributions. Regular quasiprobabilities are
constructed from characteristic functions which can be directly sampled by
balanced homodyne detection. Their negativities uncover the nonclassical
effects of general quantum states. The method is illustrated by visualizing the
nonclassical nature of a squeezed state.Comment: Significantly revised version, more emphasis on practical applicatio
Lifelong Multi-Agent Path Finding in Large-Scale Warehouses
Multi-Agent Path Finding (MAPF) is the problem of moving a team of agents to
their goal locations without collisions. In this paper, we study the lifelong
variant of MAPF, where agents are constantly engaged with new goal locations,
such as in large-scale automated warehouses. We propose a new framework
Rolling-Horizon Collision Resolution (RHCR) for solving lifelong MAPF by
decomposing the problem into a sequence of Windowed MAPF instances, where a
Windowed MAPF solver resolves collisions among the paths of the agents only
within a bounded time horizon and ignores collisions beyond it. RHCR is
particularly well suited to generating pliable plans that adapt to continually
arriving new goal locations. We empirically evaluate RHCR with a variety of
MAPF solvers and show that it can produce high-quality solutions for up to
1,000 agents (= 38.9\% of the empty cells on the map) for simulated warehouse
instances, significantly outperforming existing work.Comment: Published at AAAI 202
Cooling Performance of White Roofs in Residential Buildings
A multitude of research efforts explore the possibilities for reducing buildings' energy demand. In general, the cooling load of buildings is affected in part by the solar absorptance of roof surfaces. Therefore, new energy-efficient products with higher reflectance for the building envelope can be favorable in view of energy saving potential. In this context, this paper explores the potential for reducing building’s cooling energy demand via application of high solar reflectivity layers applied to the roof surface. For this purpose, three different prefabricated residential buildings in Novi Sad, Serbia, were selected and made subject to systematic thermal performance simulations. The computed performance indicators were then used to investigate cooling demand and overheating tendencies during summer months. The results show a significant reduction in computed cooling loads (from 4% to 37%, depending on the envisioned scenario), thus pointing to the thermal benefits of the cool roof system
Revisiting the Hanbury Brown-Twiss set-up for fractional statistics
The Hanbury Brown-Twiss experiment has proved to be an effective means of
probing statistics of particles. Here, in a set-up involving edge-state
quasiparticles in a fractional quantum Hall system, we show that a variant of
the experiment composed of two sources and two sinks can be used to unearth
fractional statistics. We find a clear cut signature of the statistics in the
equal-time current-current correlation function for quasiparticle currents
emerging from the two sources and collected at the sinks.Comment: 4 pages, 3 figure
Quantum teleportation and entanglement swapping with linear optics logic gates
We report on the usage of a linear optics phase gate for distinguishing all
four Bell states simultaneously in a quantum teleportation and entanglement
swapping protocol. This is demonstrated by full state tomography of the one and
two qubit output states of the two protocols, yielding average state fidelities
of about 0.83 and 0.77, respectively. In addition, the performance of the
teleportation channel is characterised by quantum process tomography. The non
classical properties of the entanglement swapping output states are further
confirmed by the violation of a CHSH-type Bell inequality of 2.14 on average.Comment: 11 pages, 3 figure
Direct generation of photon triplets using cascaded photon-pair sources
Non-classical states of light, such as entangled photon pairs and number
states, are essential for fundamental tests of quantum mechanics and optical
quantum technologies. The most widespread technique for creating these quantum
resources is the spontaneous parametric down-conversion (SPDC) of laser light
into photon pairs. Conservation of energy and momentum in this process, known
as phase-matching, gives rise to strong correlations which are used to produce
two-photon entanglement in various degrees of freedom. It has been a
longstanding goal of the quantum optics community to realise a source that can
produce analogous correlations in photon triplets, but of the many approaches
considered, none have been technically feasible. In this paper we report the
observation of photon triplets generated by cascaded down-conversion. Here each
triplet originates from a single pump photon, and therefore quantum
correlations will extend over all three photons in a way not achievable with
independently created photon pairs. We expect our photon-triplet source to open
up new avenues of quantum optics and become an important tool in quantum
technologies. Our source will allow experimental interrogation of novel quantum
correlations, the post-selection free generation of tripartite entanglement
without post- selection and the generation of heralded entangled-photon pairs
suitable for linear optical quantum computing. Two of the triplet photons have
a wavelength matched for optimal transmission in optical fibres, ideally suited
for three-party quantum communication. Furthermore, our results open
interesting regimes of non-linear optics, as we observe spontaneous
down-conversion pumped by single photons, an interaction also highly relevant
to optical quantum computing.Comment: 7 pages, 3 figures, 1 table; accepted by Natur
Experimental measurement-based quantum computing beyond the cluster-state model
The paradigm of measurement-based quantum computation opens new experimental
avenues to realize a quantum computer and deepens our understanding of quantum
physics. Measurement-based quantum computation starts from a highly entangled
universal resource state. For years, clusters states have been the only known
universal resources. Surprisingly, a novel framework namely quantum computation
in correlation space has opened new routes to implement measurement-based
quantum computation based on quantum states possessing entanglement properties
different from cluster states. Here we report an experimental demonstration of
every building block of such a model. With a four-qubit and a six-qubit state
as distinct from cluster states, we have realized a universal set of
single-qubit rotations, two-qubit entangling gates and further Deutsch's
algorithm. Besides being of fundamental interest, our experiment proves
in-principle the feasibility of universal measurement-based quantum computation
without using cluster states, which represents a new approach towards the
realization of a quantum computer.Comment: 26 pages, final version, comments welcom
microRNA miR-142-3p Inhibits Breast Cancer Cell Invasiveness by Synchronous Targeting of WASL, Integrin Alpha V, and Additional Cytoskeletal Elements
MicroRNAs (miRNAs, micro ribonucleic acids) are pivotal post-transcriptional regulators of gene expression. These endogenous small non-coding RNAs play significant roles in tumorigenesis and tumor progression. miR-142-3p expression is dysregulated in several breast cancer subtypes. We aimed at investigating the role of miR-142-3p in breast cancer cell invasiveness. Supported by transcriptomic Affymetrix array analysis and confirmatory investigations at the mRNA and protein level, we demonstrate that overexpression of miR-142-3p in MDA-MB-231, MDA-MB-468 and MCF-7 breast cancer cells leads to downregulation of WASL (Wiskott-Aldrich syndrome-like, protein: N-WASP), Integrin-αV, RAC1, and CFL2, molecules implicated in cytoskeletal regulation and cell motility. ROCK2, IL6ST, KLF4, PGRMC2 and ADCY9 were identified as additional targets in a subset of cell lines. Decreased Matrigel invasiveness was associated with the miR-142-3p-induced expression changes. Confocal immunofluorescence microscopy, nanoscale atomic force microscopy and digital holographic microscopy revealed a change in cell morphology as well as a reduced cell volume and size. A more cortical actin distribution and a loss of membrane protrusions were observed in cells overexpressing miR-142-3p. Luciferase activation assays confirmed direct miR-142-3p-dependent regulation of the 3’-untranslated region of ITGAV and WASL. siRNA-mediated depletion of ITGAV and WASL resulted in a significant reduction of cellular invasiveness, highlighting the contribution of these factors to the miRNA-dependent invasion phenotype. While knockdown of WASL significantly reduced the number of membrane protrusions compared to controls, knockdown of ITGAV resulted in a decreased cell volume, indicating differential contributions of these factors to the miR-142-3p-induced phenotype. Our data identify WASL, ITGAV and several additional cytoskeleton-associated molecules as novel invasion-promoting targets of miR-142-3p in breast cancer
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