3,175 research outputs found
Fitness Landscape-Based Characterisation of Nature-Inspired Algorithms
A significant challenge in nature-inspired algorithmics is the identification
of specific characteristics of problems that make them harder (or easier) to
solve using specific methods. The hope is that, by identifying these
characteristics, we may more easily predict which algorithms are best-suited to
problems sharing certain features. Here, we approach this problem using fitness
landscape analysis. Techniques already exist for measuring the "difficulty" of
specific landscapes, but these are often designed solely with evolutionary
algorithms in mind, and are generally specific to discrete optimisation. In
this paper we develop an approach for comparing a wide range of continuous
optimisation algorithms. Using a fitness landscape generation technique, we
compare six different nature-inspired algorithms and identify which methods
perform best on landscapes exhibiting specific features.Comment: 10 pages, 1 figure, submitted to the 11th International Conference on
Adaptive and Natural Computing Algorithm
Charting the circuit QED design landscape using optimal control theory
With recent improvements in coherence times, superconducting transmon qubits
have become a promising platform for quantum computing. They can be flexibly
engineered over a wide range of parameters, but also require us to identify an
efficient operating regime. Using state-of-the-art quantum optimal control
techniques, we exhaustively explore the landscape for creation and removal of
entanglement over a wide range of design parameters. We identify an optimal
operating region outside of the usually considered strongly dispersive regime,
where multiple sources of entanglement interfere simultaneously, which we name
the quasi-dispersive straddling qutrits (QuaDiSQ) regime. At a chosen point in
this region, a universal gate set is realized by applying microwave fields for
gate durations of 50 ns, with errors approaching the limit of intrinsic
transmon coherence. Our systematic quantum optimal control approach is easily
adapted to explore the parameter landscape of other quantum technology
platforms.Comment: 13 pages, 5 figures, 2 pages supplementary, 1 supplementary figur
Quantifying the Impact of Parameter Tuning on Nature-Inspired Algorithms
The problem of parameterization is often central to the effective deployment
of nature-inspired algorithms. However, finding the optimal set of parameter
values for a combination of problem instance and solution method is highly
challenging, and few concrete guidelines exist on how and when such tuning may
be performed. Previous work tends to either focus on a specific algorithm or
use benchmark problems, and both of these restrictions limit the applicability
of any findings. Here, we examine a number of different algorithms, and study
them in a "problem agnostic" fashion (i.e., one that is not tied to specific
instances) by considering their performance on fitness landscapes with varying
characteristics. Using this approach, we make a number of observations on which
algorithms may (or may not) benefit from tuning, and in which specific
circumstances.Comment: 8 pages, 7 figures. Accepted at the European Conference on Artificial
Life (ECAL) 2013, Taormina, Ital
Ono: an open platform for social robotics
In recent times, the focal point of research in robotics has shifted from industrial ro- bots toward robots that interact with humans in an intuitive and safe manner. This evolution has resulted in the subfield of social robotics, which pertains to robots that function in a human environment and that can communicate with humans in an int- uitive way, e.g. with facial expressions. Social robots have the potential to impact many different aspects of our lives, but one particularly promising application is the use of robots in therapy, such as the treatment of children with autism. Unfortunately, many of the existing social robots are neither suited for practical use in therapy nor for large scale studies, mainly because they are expensive, one-of-a-kind robots that are hard to modify to suit a specific need. We created Ono, a social robotics platform, to tackle these issues. Ono is composed entirely from off-the-shelf components and cheap materials, and can be built at a local FabLab at the fraction of the cost of other robots. Ono is also entirely open source and the modular design further encourages modification and reuse of parts of the platform
Monte Carlo Generators
The structure of events in high-energy collisions is complex and not
predictable from first principles. Event generators allow the problem to be
subdivided into more manageable pieces, some of which can be described from
first principles, while others need to be based on appropriate models with
parameters tuned to data. In these lectures we provide an overview, discuss how
matrix elements are used, introduce the machinery for initial- and final-state
parton showers, explain how matrix elements and parton showers can be combined
for optimal accuracy, introduce the concept of multiple parton--parton
interactions, comment briefly on the hadronization issue, and provide an
outlook for the future.Comment: 23 pages, lectures presented at the 2006 European School of
High-Energy Physics, Aronsborg, Sweden, 18 June -- 1 July 200
Exploring Interacting Quantum Many-Body Systems by Experimentally Creating Continuous Matrix Product States in Superconducting Circuits
Improving the understanding of strongly correlated quantum many body systems
such as gases of interacting atoms or electrons is one of the most important
challenges in modern condensed matter physics, materials research and
chemistry. Enormous progress has been made in the past decades in developing
both classical and quantum approaches to calculate, simulate and experimentally
probe the properties of such systems. In this work we use a combination of
classical and quantum methods to experimentally explore the properties of an
interacting quantum gas by creating experimental realizations of continuous
matrix product states - a class of states which has proven extremely powerful
as a variational ansatz for numerical simulations. By systematically preparing
and probing these states using a circuit quantum electrodynamics (cQED) system
we experimentally determine a good approximation to the ground-state wave
function of the Lieb-Liniger Hamiltonian, which describes an interacting Bose
gas in one dimension. Since the simulated Hamiltonian is encoded in the
measurement observable rather than the controlled quantum system, this approach
has the potential to apply to exotic models involving multicomponent
interacting fields. Our findings also hint at the possibility of experimentally
exploring general properties of matrix product states and entanglement theory.
The scheme presented here is applicable to a broad range of systems exploiting
strong and tunable light-matter interactions.Comment: 11 pages, 9 figure
- …