61,720 research outputs found
Noise-assisted Multibit Storage Device
In this paper we extend our investigations on noise-assisted storage devices
through the experimental study of a loop composed of a single Schmitt trigger
and an element that introduces a finite delay. We show that such a system
allows the storage of several bits and does so more efficiently for an
intermediate range of noise intensities. Finally, we study the probability of
erroneous information retrieval as a function of elapsed time and show a way
for predicting device performance independently of the number of stored bits.Comment: 5 figure
Energy challenges for ICT
The energy consumption from the expanding use of information and communications technology (ICT) is unsustainable with present drivers, and it will impact heavily on the future climate change. However, ICT devices have the potential to contribute signi - cantly to the reduction of CO2 emission and enhance resource e ciency in other sectors, e.g., transportation (through intelligent transportation and advanced driver assistance systems and self-driving vehicles), heating (through smart building control), and manu- facturing (through digital automation based on smart autonomous sensors). To address the energy sustainability of ICT and capture the full potential of ICT in resource e - ciency, a multidisciplinary ICT-energy community needs to be brought together cover- ing devices, microarchitectures, ultra large-scale integration (ULSI), high-performance computing (HPC), energy harvesting, energy storage, system design, embedded sys- tems, e cient electronics, static analysis, and computation. In this chapter, we introduce challenges and opportunities in this emerging eld and a common framework to strive towards energy-sustainable ICT
What is a quantum computer, and how do we build one?
The DiVincenzo criteria for implementing a quantum computer have been seminal
in focussing both experimental and theoretical research in quantum information
processing. These criteria were formulated specifically for the circuit model
of quantum computing. However, several new models for quantum computing
(paradigms) have been proposed that do not seem to fit the criteria well. The
question is therefore what are the general criteria for implementing quantum
computers. To this end, a formal operational definition of a quantum computer
is introduced. It is then shown that according to this definition a device is a
quantum computer if it obeys the following four criteria: Any quantum computer
must (1) have a quantum memory; (2) facilitate a controlled quantum evolution
of the quantum memory; (3) include a method for cooling the quantum memory; and
(4) provide a readout mechanism for subsets of the quantum memory. The criteria
are met when the device is scalable and operates fault-tolerantly. We discuss
various existing quantum computing paradigms, and how they fit within this
framework. Finally, we lay out a roadmap for selecting an avenue towards
building a quantum computer. This is summarized in a decision tree intended to
help experimentalists determine the most natural paradigm given a particular
physical implementation
Short Block-length Codes for Ultra-Reliable Low-Latency Communications
This paper reviews the state of the art channel coding techniques for
ultra-reliable low latency communication (URLLC). The stringent requirements of
URLLC services, such as ultra-high reliability and low latency, have made it
the most challenging feature of the fifth generation (5G) mobile systems. The
problem is even more challenging for the services beyond the 5G promise, such
as tele-surgery and factory automation, which require latencies less than 1ms
and failure rate as low as . The very low latency requirements of
URLLC do not allow traditional approaches such as re-transmission to be used to
increase the reliability. On the other hand, to guarantee the delay
requirements, the block length needs to be small, so conventional channel
codes, originally designed and optimised for moderate-to-long block-lengths,
show notable deficiencies for short blocks. This paper provides an overview on
channel coding techniques for short block lengths and compares them in terms of
performance and complexity. Several important research directions are
identified and discussed in more detail with several possible solutions.Comment: Accepted for publication in IEEE Communications Magazin
Scalable communication for high-order stencil computations using CUDA-aware MPI
Modern compute nodes in high-performance computing provide a tremendous level
of parallelism and processing power. However, as arithmetic performance has
been observed to increase at a faster rate relative to memory and network
bandwidths, optimizing data movement has become critical for achieving strong
scaling in many communication-heavy applications. This performance gap has been
further accentuated with the introduction of graphics processing units, which
can provide by multiple factors higher throughput in data-parallel tasks than
central processing units. In this work, we explore the computational aspects of
iterative stencil loops and implement a generic communication scheme using
CUDA-aware MPI, which we use to accelerate magnetohydrodynamics simulations
based on high-order finite differences and third-order Runge-Kutta integration.
We put particular focus on improving intra-node locality of workloads. In
comparison to a theoretical performance model, our implementation exhibits
strong scaling from one to devices at -- efficiency in
sixth-order stencil computations when the problem domain consists of
-- cells.Comment: 17 pages, 15 figure
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