13,031 research outputs found
CMOL: Second Life for Silicon?
This report is a brief review of the recent work on architectures for the
prospective hybrid CMOS/nanowire/ nanodevice ("CMOL") circuits including
digital memories, reconfigurable Boolean-logic circuits, and mixed-signal
neuromorphic networks. The basic idea of CMOL circuits is to combine the
advantages of CMOS technology (including its flexibility and high fabrication
yield) with the extremely high potential density of molecular-scale
two-terminal nanodevices. Relatively large critical dimensions of CMOS
components and the "bottom-up" approach to nanodevice fabrication may keep CMOL
fabrication costs at affordable level. At the same time, the density of active
devices in CMOL circuits may be as high as 1012 cm2 and that they may provide
an unparalleled information processing performance, up to 1020 operations per
cm2 per second, at manageable power consumption.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
On model checking data-independent systems with arrays without reset
A system is data-independent with respect to a data type X iff the operations
it can perform on values of type X are restricted to just equality testing. The
system may also store, input and output values of type X. We study model
checking of systems which are data-independent with respect to two distinct
type variables X and Y, and may in addition use arrays with indices from X and
values from Y . Our main interest is the following parameterised model-checking
problem: whether a given program satisfies a given temporal-logic formula for
all non-empty nite instances of X and Y . Initially, we consider instead the
abstraction where X and Y are infinite and where partial functions with finite
domains are used to model arrays. Using a translation to data-independent
systems without arrays, we show that the u-calculus model-checking problem is
decidable for these systems. From this result, we can deduce properties of all
systems with finite instances of X and Y . We show that there is a procedure
for the above parameterised model-checking problem of the universal fragment of
the u-calculus, such that it always terminates but may give false negatives. We
also deduce that the parameterised model-checking problem of the universal
disjunction-free fragment of the u-calculus is decidable. Practical motivations
for model checking data-independent systems with arrays include verification of
memory and cache systems, where X is the type of memory addresses, and Y the
type of storable values. As an example we verify a fault-tolerant memory
interface over a set of unreliable memories.Comment: Appeared in Theory and Practice of Logic Programming, vol. 4, no.
5&6, 200
Unforgeable Noise-Tolerant Quantum Tokens
The realization of devices which harness the laws of quantum mechanics
represents an exciting challenge at the interface of modern technology and
fundamental science. An exemplary paragon of the power of such quantum
primitives is the concept of "quantum money". A dishonest holder of a quantum
bank-note will invariably fail in any forging attempts; indeed, under
assumptions of ideal measurements and decoherence-free memories such security
is guaranteed by the no-cloning theorem. In any practical situation, however,
noise, decoherence and operational imperfections abound. Thus, the development
of secure "quantum money"-type primitives capable of tolerating realistic
infidelities is of both practical and fundamental importance. Here, we propose
a novel class of such protocols and demonstrate their tolerance to noise;
moreover, we prove their rigorous security by determining tight fidelity
thresholds. Our proposed protocols require only the ability to prepare, store
and measure single qubit quantum memories, making their experimental
realization accessible with current technologies.Comment: 18 pages, 5 figure
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MADX: Memristors-As-Drivers for Crossbar logic
Memristors have the potential to not only replace conventional memory, but also to open up new design possibilities because they store 1s and 0s as resistances rather than voltages. A memristor architecture that has attracted interest for its versatility and ease of integration with existing CMOS technologies is the crossbar array. In this paper, I modify the MAD scheme to create the MADX scheme for performing basic logic operations within a crossbar array. Then, I compare this scheme against two of the most well-known schemes, MAGIC and IMPLY. In the case study of a full-adder, both a one-bit and an 8-bit version, the MADX scheme achieves lower latency and substantially lower area requirements than both MAGIC and IMPLY. This is because it is more flexible about storing output values than either, does not destroy input values unlike IMPLY, and has more basic operations. In particular, it has XOR, which neither IMPLY nor MAGIC have and is useful for additionPlan II Honors Progra
Neural Networks retrieving Boolean patterns in a sea of Gaussian ones
Restricted Boltzmann Machines are key tools in Machine Learning and are
described by the energy function of bipartite spin-glasses. From a statistical
mechanical perspective, they share the same Gibbs measure of Hopfield networks
for associative memory. In this equivalence, weights in the former play as
patterns in the latter. As Boltzmann machines usually require real weights to
be trained with gradient descent like methods, while Hopfield networks
typically store binary patterns to be able to retrieve, the investigation of a
mixed Hebbian network, equipped with both real (e.g., Gaussian) and discrete
(e.g., Boolean) patterns naturally arises. We prove that, in the challenging
regime of a high storage of real patterns, where retrieval is forbidden, an
extra load of Boolean patterns can still be retrieved, as long as the ratio
among the overall load and the network size does not exceed a critical
threshold, that turns out to be the same of the standard
Amit-Gutfreund-Sompolinsky theory. Assuming replica symmetry, we study the case
of a low load of Boolean patterns combining the stochastic stability and
Hamilton-Jacobi interpolating techniques. The result can be extended to the
high load by a non rigorous but standard replica computation argument.Comment: 16 pages, 1 figur
X-SRAM: Enabling In-Memory Boolean Computations in CMOS Static Random Access Memories
Silicon-based Static Random Access Memories (SRAM) and digital Boolean logic
have been the workhorse of the state-of-art computing platforms. Despite
tremendous strides in scaling the ubiquitous metal-oxide-semiconductor
transistor, the underlying \textit{von-Neumann} computing architecture has
remained unchanged. The limited throughput and energy-efficiency of the
state-of-art computing systems, to a large extent, results from the well-known
\textit{von-Neumann bottleneck}. The energy and throughput inefficiency of the
von-Neumann machines have been accentuated in recent times due to the present
emphasis on data-intensive applications like artificial intelligence, machine
learning \textit{etc}. A possible approach towards mitigating the overhead
associated with the von-Neumann bottleneck is to enable \textit{in-memory}
Boolean computations. In this manuscript, we present an augmented version of
the conventional SRAM bit-cells, called \textit{the X-SRAM}, with the ability
to perform in-memory, vector Boolean computations, in addition to the usual
memory storage operations. We propose at least six different schemes for
enabling in-memory vector computations including NAND, NOR, IMP (implication),
XOR logic gates with respect to different bit-cell topologies the 8T cell
and the 8T Differential cell. In addition, we also present a novel
\textit{`read-compute-store'} scheme, wherein the computed Boolean function can
be directly stored in the memory without the need of latching the data and
carrying out a subsequent write operation. The feasibility of the proposed
schemes has been verified using predictive transistor models and Monte-Carlo
variation analysis.Comment: This article has been accepted in a future issue of IEEE Transactions
on Circuits and Systems-I: Regular Paper
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