23,751 research outputs found
Meso-scale FDM material layout design strategies under manufacturability constraints and fracture conditions
In the manufacturability-driven design (MDD) perspective, manufacturability of the product or system is the most important of the design requirements. In addition to being able to ensure that complex designs (e.g., topology optimization) are manufacturable with a given process or process family, MDD also helps mechanical designers to take advantage of unique process-material effects generated during manufacturing. One of the most recognizable examples of this comes from the scanning-type family of additive manufacturing (AM) processes; the most notable and familiar member of this family is the fused deposition modeling (FDM) or fused filament fabrication (FFF) process. This process works by selectively depositing uniform, approximately isotropic beads or elements of molten thermoplastic material (typically structural engineering plastics) in a series of pre-specified traces to build each layer of the part. There are many interesting 2-D and 3-D mechanical design problems that can be explored by designing the layout of these elements. The resulting structured, hierarchical material (which is both manufacturable and customized layer-by-layer within the limits of the process and material) can be defined as a manufacturing process-driven structured material (MPDSM). This dissertation explores several practical methods for designing these element layouts for 2-D and 3-D meso-scale mechanical problems, focusing ultimately on design-for-fracture. Three different fracture conditions are explored: (1) cases where a crack must be prevented or stopped, (2) cases where the crack must be encouraged or accelerated, and (3) cases where cracks must grow in a simple pre-determined pattern. Several new design tools, including a mapping method for the FDM manufacturability constraints, three major literature reviews, the collection, organization, and analysis of several large (qualitative and quantitative) multi-scale datasets on the fracture behavior of FDM-processed materials, some new experimental equipment, and the refinement of a fast and simple g-code generator based on commercially-available software, were developed and refined to support the design of MPDSMs under fracture conditions. The refined design method and rules were experimentally validated using a series of case studies (involving both design and physical testing of the designs) at the end of the dissertation. Finally, a simple design guide for practicing engineers who are not experts in advanced solid mechanics nor process-tailored materials was developed from the results of this project.U of I OnlyAuthor's request
Applications of nonlinear four-wave mixing in optical communication
In this paper I will briefly review some applications of nonlinear four-wave-mixing in optical fibers and silicon-nitride waveguides. This includes ultrafast all-optical waveform sampling and ‘noiseless’ phase-sensitive optical amplification which have been demonstrated to enable signal recovery at very low optical powers
Bayesian estimation for Bell state rotations
This paper explores the effect of three-dimensional rotations on two-qubit Bell states and proposes a Bayesian method for the estimation of the parameters of the rotation. We use a particle filter to estimate the parameters of the rotation from a sequence of Bell state measurements, and we demonstrate that the resultant improvement over the optimal single qubit case approaches the 2 factor that is consistent with the Heisenberg limit. We also demonstrate how the accuracy of the estimation method is a function of the purity of mixed states.</jats:p
Remote preparation of optical cat states based on Gaussian entanglement
Remote state preparation enables one to prepare and manipulate quantum state
non-locally. As an essential quantum resource, optical cat state is usually
prepared locally by subtracting photons from a squeezed vacuum state. For
remote quantum information processing, it is essential to prepare and
manipulate optical cat states remotely based on Gaussian entanglement, which
remains a challenge. Here, we present experimental preparation of optical cat
states based on a remotely distributed two-mode Gaussian entangled state in a
lossy channel. By performing photon subtraction and homodyne projective
measurement at Alice's station, an optical cat state is prepared remotely at
Bob's station. Furthermore, the prepared cat state is rotated by changing
Alice's measurement basis of homodyne detection, which demonstrates the remote
manipulation of it. By distributing two modes of the two-mode Gaussian
entangled state in lossy channels, we demonstrate that the remotely prepared
cat state can tolerate much more loss in Alice's channel than that in Bob's
channel. We also show that cat states with amplitudes larger than 2 can be
prepared by increasing the squeezing level and subtracting photon numbers. Our
results make a crucial step toward remote hybrid quantum information processing
involving discrete- and continuous-variable techniques
Boosting entanglement growth of many-body localization by superpositions of disorder
Many-body localization (MBL) can occur when strong disorders prevent an
interacting system from thermalization. To study the dynamics of such systems,
it is typically necessary to perform an ensemble average over many different
disorder configurations. Previous works have utilized an algorithm in which
different disorder profiles are mapped into a quantum ancilla. By preparing the
ancilla in a quantum superposition state, quantum parallelism can be harnessed
to obtain the ensemble average in a single computation run. In this work, we
modify this algorithm by performing a measurement on the ancilla. This enables
the determination of conditional dynamics not only by the ensemble average but
also by the quantum interference effect. Using a phenomenological analysis
based on local integrals of motion, we demonstrate that this protocol can lead
to an enhancement of the dephasing effect and a boost in the entanglement
growth for systems in the deep MBL phase. We also present numerical simulations
of the random XXZ model where this enhancement is also present in a smaller
disorder strength, beyond the deep MBL regime.Comment: 7 pages, 4 figure
AI-assisted Automated Workflow for Real-time X-ray Ptychography Data Analysis via Federated Resources
We present an end-to-end automated workflow that uses large-scale remote
compute resources and an embedded GPU platform at the edge to enable
AI/ML-accelerated real-time analysis of data collected for x-ray ptychography.
Ptychography is a lensless method that is being used to image samples through a
simultaneous numerical inversion of a large number of diffraction patterns from
adjacent overlapping scan positions. This acquisition method can enable
nanoscale imaging with x-rays and electrons, but this often requires very large
experimental datasets and commensurately high turnaround times, which can limit
experimental capabilities such as real-time experimental steering and
low-latency monitoring. In this work, we introduce a software system that can
automate ptychography data analysis tasks. We accelerate the data analysis
pipeline by using a modified version of PtychoNN -- an ML-based approach to
solve phase retrieval problem that shows two orders of magnitude speedup
compared to traditional iterative methods. Further, our system coordinates and
overlaps different data analysis tasks to minimize synchronization overhead
between different stages of the workflow. We evaluate our workflow system with
real-world experimental workloads from the 26ID beamline at Advanced Photon
Source and ThetaGPU cluster at Argonne Leadership Computing Resources.Comment: 7 pages, 1 figure, to be published in High Performance Computing for
Imaging Conference, Electronic Imaging (HPCI 2023
Quantum Zeno and anti-Zeno effects in the dynamics of non-degenerate hyper-Raman processes coupled to two linear waveguides
The effect of the presence of two probe waveguides on the dynamics of
hyper-Raman processes is studied in terms of quantum Zeno and anti-Zeno
effects. Specifically, the enhancement (diminution) of the evolution of the
hyper-Raman processes due to interaction with the probe waveguides via
evanescent waves is viewed as quantum Zeno (anti-Zeno) effect. We considered
the two probe waveguides interacting with only one of the optical modes at a
time. For instance, as a specific scenario, it is considered that the two
non-degenerate pump modes interact with each probe waveguide linearly while
Stokes and anti-Stokes modes do not interact with the probes. Similarly, in
another scenario, we assumed both the probe waveguides interact with Stokes
(anti-Stokes) mode simultaneously. The present results show that quantum Zeno
(anti-Zeno) effect is associated with phase-matching (mismatching). However, we
did not find any relation between the presence of the quantum Zeno effect and
antibunching in the bosonic modes present in the hyper-Raman processes.Comment: Dynamics of hyper-Raman processes is studied in terms of quantum Zeno
and anti-Zeno effect
Quantifying the Expressive Capacity of Quantum Systems: Fundamental Limits and Eigentasks
The expressive capacity of quantum systems for machine learning is limited by
quantum sampling noise incurred during measurement. Although it is generally
believed that noise limits the resolvable capacity of quantum systems, the
precise impact of noise on learning is not yet fully understood. We present a
mathematical framework for evaluating the available expressive capacity of
general quantum systems from a finite number of measurements, and provide a
methodology for extracting the extrema of this capacity, its eigentasks.
Eigentasks are a native set of functions that a given quantum system can
approximate with minimal error. We show that extracting low-noise eigentasks
leads to improved performance for machine learning tasks such as
classification, displaying robustness to overfitting. We obtain a tight bound
on the expressive capacity, and present analyses suggesting that correlations
in the measured quantum system enhance learning capacity by reducing noise in
eigentasks. These results are supported by experiments on superconducting
quantum processors. Our findings have broad implications for quantum machine
learning and sensing applications.Comment: 7 + 21 pages, 4 + 12 figures, 1 tabl
The Metaverse: Survey, Trends, Novel Pipeline Ecosystem & Future Directions
The Metaverse offers a second world beyond reality, where boundaries are
non-existent, and possibilities are endless through engagement and immersive
experiences using the virtual reality (VR) technology. Many disciplines can
benefit from the advancement of the Metaverse when accurately developed,
including the fields of technology, gaming, education, art, and culture.
Nevertheless, developing the Metaverse environment to its full potential is an
ambiguous task that needs proper guidance and directions. Existing surveys on
the Metaverse focus only on a specific aspect and discipline of the Metaverse
and lack a holistic view of the entire process. To this end, a more holistic,
multi-disciplinary, in-depth, and academic and industry-oriented review is
required to provide a thorough study of the Metaverse development pipeline. To
address these issues, we present in this survey a novel multi-layered pipeline
ecosystem composed of (1) the Metaverse computing, networking, communications
and hardware infrastructure, (2) environment digitization, and (3) user
interactions. For every layer, we discuss the components that detail the steps
of its development. Also, for each of these components, we examine the impact
of a set of enabling technologies and empowering domains (e.g., Artificial
Intelligence, Security & Privacy, Blockchain, Business, Ethics, and Social) on
its advancement. In addition, we explain the importance of these technologies
to support decentralization, interoperability, user experiences, interactions,
and monetization. Our presented study highlights the existing challenges for
each component, followed by research directions and potential solutions. To the
best of our knowledge, this survey is the most comprehensive and allows users,
scholars, and entrepreneurs to get an in-depth understanding of the Metaverse
ecosystem to find their opportunities and potentials for contribution
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