29,175 research outputs found
Acoustic Phonon-Assisted Resonant Tunneling via Single Impurities
We perform the investigations of the resonant tunneling via impurities
embedded in the AlAs barrier of a single GaAs/AlGaAs heterostructure. In the
characteristics measured at 30mK, the contribution of individual donors
is resolved and the fingerprints of phonon assistance in the tunneling process
are seen. The latter is confirmed by detailed analysis of the tunneling rates
and the modeling of the resonant tunneling contribution to the current.
Moreover, fluctuations of the local structure of the DOS (LDOS) and Fermi edge
singularities are observed.Comment: accepted in Phys. Rev.
Few-Shot Bayesian Imitation Learning with Logical Program Policies
Humans can learn many novel tasks from a very small number (1--5) of
demonstrations, in stark contrast to the data requirements of nearly tabula
rasa deep learning methods. We propose an expressive class of policies, a
strong but general prior, and a learning algorithm that, together, can learn
interesting policies from very few examples. We represent policies as logical
combinations of programs drawn from a domain-specific language (DSL), define a
prior over policies with a probabilistic grammar, and derive an approximate
Bayesian inference algorithm to learn policies from demonstrations. In
experiments, we study five strategy games played on a 2D grid with one shared
DSL. After a few demonstrations of each game, the inferred policies generalize
to new game instances that differ substantially from the demonstrations. Our
policy learning is 20--1,000x more data efficient than convolutional and fully
convolutional policy learning and many orders of magnitude more computationally
efficient than vanilla program induction. We argue that the proposed method is
an apt choice for tasks that have scarce training data and feature significant,
structured variation between task instances.Comment: AAAI 202
Plasma Nanoscience: from Nano-Solids in Plasmas to Nano-Plasmas in Solids
The unique plasma-specific features and physical phenomena in the
organization of nanoscale solid-state systems in a broad range of elemental
composition, structure, and dimensionality are critically reviewed. These
effects lead to the possibility to localize and control energy and matter at
nanoscales and to produce self-organized nano-solids with highly unusual and
superior properties. A unifying conceptual framework based on the control of
production, transport, and self-organization of precursor species is introduced
and a variety of plasma-specific non-equilibrium and kinetics-driven phenomena
across the many temporal and spatial scales is explained. When the plasma is
localized to micrometer and nanometer dimensions, new emergent phenomena arise.
The examples range from semiconducting quantum dots and nanowires, chirality
control of single-walled carbon nanotubes, ultra-fine manipulation of
graphenes, nano-diamond, and organic matter, to nano-plasma effects and
nano-plasmas of different states of matter.Comment: This is an essential interdisciplinary reference which can be used by
both advanced and early career researchers as well as in undergraduate
teaching and postgraduate research trainin
Reactive Exploration to Cope with Non-Stationarity in Lifelong Reinforcement Learning
In lifelong learning, an agent learns throughout its entire life without
resets, in a constantly changing environment, as we humans do. Consequently,
lifelong learning comes with a plethora of research problems such as continual
domain shifts, which result in non-stationary rewards and environment dynamics.
These non-stationarities are difficult to detect and cope with due to their
continuous nature. Therefore, exploration strategies and learning methods are
required that are capable of tracking the steady domain shifts, and adapting to
them. We propose Reactive Exploration to track and react to continual domain
shifts in lifelong reinforcement learning, and to update the policy
correspondingly. To this end, we conduct experiments in order to investigate
different exploration strategies. We empirically show that representatives of
the policy-gradient family are better suited for lifelong learning, as they
adapt more quickly to distribution shifts than Q-learning. Thereby,
policy-gradient methods profit the most from Reactive Exploration and show good
results in lifelong learning with continual domain shifts. Our code is
available at: https://github.com/ml-jku/reactive-exploration.Comment: CoLLAs 202
Intelligent systems in manufacturing: current developments and future prospects
Global competition and rapidly changing customer requirements are demanding increasing changes in manufacturing environments. Enterprises are required to constantly redesign their products and continuously reconfigure their manufacturing systems. Traditional approaches to manufacturing systems do not fully satisfy this new situation. Many authors have proposed that artificial intelligence will bring the flexibility and efficiency needed by manufacturing systems. This paper is a review of artificial intelligence techniques used in manufacturing systems. The paper first defines the components of a simplified intelligent manufacturing systems (IMS), the different Artificial Intelligence (AI) techniques to be considered and then shows how these AI techniques are used for the components of IMS
Multi-mode ultra-strong coupling in circuit quantum electrodynamics
With the introduction of superconducting circuits into the field of quantum
optics, many novel experimental demonstrations of the quantum physics of an
artificial atom coupled to a single-mode light field have been realized.
Engineering such quantum systems offers the opportunity to explore extreme
regimes of light-matter interaction that are inaccessible with natural systems.
For instance the coupling strength can be increased until it is comparable
with the atomic or mode frequency and the atom can be coupled to
multiple modes which has always challenged our understanding of light-matter
interaction. Here, we experimentally realize the first Transmon qubit in the
ultra-strong coupling regime, reaching coupling ratios of
and we measure multi-mode interactions through a hybridization of the qubit up
to the fifth mode of the resonator. This is enabled by a qubit with 88% of its
capacitance formed by a vacuum-gap capacitance with the center conductor of a
coplanar waveguide resonator. In addition to potential applications in quantum
information technologies due to its small size and localization of electric
fields in vacuum, this new architecture offers the potential to further explore
the novel regime of multi-mode ultra-strong coupling.Comment: 15 pages, 9 figure
An Architectural Approach to Ensuring Consistency in Hierarchical Execution
Hierarchical task decomposition is a method used in many agent systems to
organize agent knowledge. This work shows how the combination of a hierarchy
and persistent assertions of knowledge can lead to difficulty in maintaining
logical consistency in asserted knowledge. We explore the problematic
consequences of persistent assumptions in the reasoning process and introduce
novel potential solutions. Having implemented one of the possible solutions,
Dynamic Hierarchical Justification, its effectiveness is demonstrated with an
empirical analysis
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