3,262 research outputs found
Synthesis and Optimization of Reversible Circuits - A Survey
Reversible logic circuits have been historically motivated by theoretical
research in low-power electronics as well as practical improvement of
bit-manipulation transforms in cryptography and computer graphics. Recently,
reversible circuits have attracted interest as components of quantum
algorithms, as well as in photonic and nano-computing technologies where some
switching devices offer no signal gain. Research in generating reversible logic
distinguishes between circuit synthesis, post-synthesis optimization, and
technology mapping. In this survey, we review algorithmic paradigms ---
search-based, cycle-based, transformation-based, and BDD-based --- as well as
specific algorithms for reversible synthesis, both exact and heuristic. We
conclude the survey by outlining key open challenges in synthesis of reversible
and quantum logic, as well as most common misconceptions.Comment: 34 pages, 15 figures, 2 table
Limits on Fundamental Limits to Computation
An indispensable part of our lives, computing has also become essential to
industries and governments. Steady improvements in computer hardware have been
supported by periodic doubling of transistor densities in integrated circuits
over the last fifty years. Such Moore scaling now requires increasingly heroic
efforts, stimulating research in alternative hardware and stirring controversy.
To help evaluate emerging technologies and enrich our understanding of
integrated-circuit scaling, we review fundamental limits to computation: in
manufacturing, energy, physical space, design and verification effort, and
algorithms. To outline what is achievable in principle and in practice, we
recall how some limits were circumvented, compare loose and tight limits. We
also point out that engineering difficulties encountered by emerging
technologies may indicate yet-unknown limits.Comment: 15 pages, 4 figures, 1 tabl
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
Photonic circuits for generating modal, spectral, and polarization entanglement
We consider the design of photonic circuits that make use of Ti:LiNbO
diffused channel waveguides for generating photons with various combinations of
modal, spectral, and polarization entanglement. Down-converted photon pairs are
generated via spontaneous optical parametric down-conversion (SPDC) in a
two-mode waveguide. We study a class of photonic circuits comprising: 1) a
nonlinear periodically poled two-mode waveguide structure, 2) a set of
single-mode and two-mode waveguide-based couplers arranged in such a way that
they suitably separate the three photons comprising the SPDC process, and, for
some applications, 3) a holographic Bragg grating that acts as a dichroic
reflector. The first circuit produces frequency-degenerate down-converted
photons, each with even spatial parity, in two separate single-mode waveguides.
Changing the parameters of the elements allows this same circuit to produce two
nondegenerate down-converted photons that are entangled in frequency or
simultaneously entangled in frequency and polarization. The second photonic
circuit is designed to produce modal entanglement by distinguishing the photons
on the basis of their frequencies. A modified version of this circuit can be
used to generate photons that are doubly entangled in mode number and
polarization. The third photonic circuit is designed to manage dispersion by
converting modal, spectral, and polarization entanglement into path
entanglement
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