4,661 research outputs found
Quantum-enhanced reinforcement learning for finite-episode games with discrete state spaces
Quantum annealing algorithms belong to the class of metaheuristic tools,
applicable for solving binary optimization problems. Hardware implementations
of quantum annealing, such as the quantum annealing machines produced by D-Wave
Systems, have been subject to multiple analyses in research, with the aim of
characterizing the technology's usefulness for optimization and sampling tasks.
Here, we present a way to partially embed both Monte Carlo policy iteration for
finding an optimal policy on random observations, as well as how to embed (n)
sub-optimal state-value functions for approximating an improved state-value
function given a policy for finite horizon games with discrete state spaces on
a D-Wave 2000Q quantum processing unit (QPU). We explain how both problems can
be expressed as a quadratic unconstrained binary optimization (QUBO) problem,
and show that quantum-enhanced Monte Carlo policy evaluation allows for finding
equivalent or better state-value functions for a given policy with the same
number episodes compared to a purely classical Monte Carlo algorithm.
Additionally, we describe a quantum-classical policy learning algorithm. Our
first and foremost aim is to explain how to represent and solve parts of these
problems with the help of the QPU, and not to prove supremacy over every
existing classical policy evaluation algorithm.Comment: 17 pages, 7 figure
Optimization and evaluation of variability in the programming window of a flash cell with molecular metal-oxide storage
We report a modeling study of a conceptual nonvolatile memory cell based on inorganic molecular metal-oxide clusters as a storage media embedded in the gate dielectric of a MOSFET. For the purpose of this paper, we developed a multiscale simulation framework that enables the evaluation of variability in the programming window of a flash cell with sub-20-nm gate length. Furthermore, we studied the threshold voltage variability due to random dopant fluctuations and fluctuations in the distribution of the molecular clusters in the cell. The simulation framework and the general conclusions of our work are transferrable to flash cells based on alternative molecules used for a storage media
Multi-level, Forming Free, Bulk Switching Trilayer RRAM for Neuromorphic Computing at the Edge
Resistive memory-based reconfigurable systems constructed by CMOS-RRAM
integration hold great promise for low energy and high throughput neuromorphic
computing. However, most RRAM technologies relying on filamentary switching
suffer from variations and noise leading to computational accuracy loss,
increased energy consumption, and overhead by expensive program and verify
schemes. Low ON-state resistance of filamentary RRAM devices further increases
the energy consumption due to high-current read and write operations, and
limits the array size and parallel multiply & accumulate operations.
High-forming voltages needed for filamentary RRAM are not compatible with
advanced CMOS technology nodes. To address all these challenges, we developed a
forming-free and bulk switching RRAM technology based on a trilayer metal-oxide
stack. We systematically engineered a trilayer metal-oxide RRAM stack and
investigated the switching characteristics of RRAM devices with varying
thicknesses and oxygen vacancy distributions across the trilayer to achieve
reliable bulk switching without any filament formation. We demonstrated bulk
switching operation at megaohm regime with high current nonlinearity and
programmed up to 100 levels without compliance current. We developed a
neuromorphic compute-in-memory platform based on trilayer bulk RRAM crossbars
by combining energy-efficient switched-capacitor voltage sensing circuits with
differential encoding of weights to experimentally demonstrate high-accuracy
matrix-vector multiplication. We showcased the computational capability of bulk
RRAM crossbars by implementing a spiking neural network model for an autonomous
navigation/racing task. Our work addresses challenges posed by existing RRAM
technologies and paves the way for neuromorphic computing at the edge under
strict size, weight, and power constraints
An overview of decision table literature 1982-1995.
This report gives an overview of the literature on decision tables over the past 15 years. As much as possible, for each reference, an author supplied abstract, a number of keywords and a classification are provided. In some cases own comments are added. The purpose of these comments is to show where, how and why decision tables are used. The literature is classified according to application area, theoretical versus practical character, year of publication, country or origin (not necessarily country of publication) and the language of the document. After a description of the scope of the interview, classification results and the classification by topic are presented. The main body of the paper is the ordered list of publications with abstract, classification and comments.
One-dimensional many-body entangled open quantum systems with tensor network methods
We present a collection of methods to simulate entangled dynamics of open
quantum systems governed by the Lindblad equation with tensor network methods.
Tensor network methods using matrix product states have been proven very useful
to simulate many-body quantum systems and have driven many innovations in
research. Since the matrix product state design is tailored for closed
one-dimensional systems governed by the Schr\"odinger equation, the next step
for many-body quantum dynamics is the simulation of open quantum systems. We
review the three dominant approaches to the simulation of open quantum systems
via the Lindblad master equation: quantum trajectories, matrix product density
operators, and locally purified tensor networks. Selected examples guide
possible applications of the methods and serve moreover as a benchmark between
the techniques. These examples include the finite temperature states of the
transverse quantum Ising model, the dynamics of an exciton traveling under the
influence of spontaneous emission and dephasing, and a double-well potential
simulated with the Bose-Hubbard model including dephasing. We analyze which
approach is favorable leading to the conclusion that a complete set of all
three methods is most beneficial, push- ing the limits of different scenarios.
The convergence studies using analytical results for macroscopic variables and
exact diagonalization methods as comparison, show, for example, that matrix
product density operators are favorable for the exciton problem in our study.
All three methods access the same library, i.e., the software package Open
Source Matrix Product States, allowing us to have a meaningful comparison
between the approaches based on the selected examples. For example, tensor
operations are accessed from the same subroutines and with the same
optimization eliminating one possible bias in a comparison of such numerical
methods.Comment: 24 pages, 8 figures. Small extension of time evolution section and
moving quantum simulators to introduction in comparison to v
Stochastics global optimization methods and their applications in Chemical Engineering
Ph.DDOCTOR OF PHILOSOPH
- …