5,038 research outputs found
Variable - temperature scanning optical and force microscope
The implementation of a scanning microscope capable of working in confocal,
atomic force and apertureless near field configurations is presented. The
microscope is designed to operate in the temperature range 4 - 300 K, using
conventional helium flow cryostats. In AFM mode, the distance between the
sample and an etched tungsten tip is controlled by a self - sensing
piezoelectric tuning fork. The vertical position of both the AFM head and
microscope objective can be accurately controlled using piezoelectric coarse
approach motors. The scanning is performed using a compact XYZ stage, while the
AFM and optical head are kept fixed, allowing scanning probe and optical
measurements to be acquired simultaneously and in concert. The free optical
axis of the microscope enables both reflection and transmission experiments to
be performed.Comment: 24 pages, 9 figures, submitted to the journal "Review of Scientific
Instruments
Gorilla: Large Language Model Connected with Massive APIs
Large Language Models (LLMs) have seen an impressive wave of advances
recently, with models now excelling in a variety of tasks, such as mathematical
reasoning and program synthesis. However, their potential to effectively use
tools via API calls remains unfulfilled. This is a challenging task even for
today's state-of-the-art LLMs such as GPT-4, largely due to their inability to
generate accurate input arguments and their tendency to hallucinate the wrong
usage of an API call. We release Gorilla, a finetuned LLaMA-based model that
surpasses the performance of GPT-4 on writing API calls. When combined with a
document retriever, Gorilla demonstrates a strong capability to adapt to
test-time document changes, enabling flexible user updates or version changes.
It also substantially mitigates the issue of hallucination, commonly
encountered when prompting LLMs directly. To evaluate the model's ability, we
introduce APIBench, a comprehensive dataset consisting of HuggingFace,
TorchHub, and TensorHub APIs. The successful integration of the retrieval
system with Gorilla demonstrates the potential for LLMs to use tools more
accurately, keep up with frequently updated documentation, and consequently
increase the reliability and applicability of their outputs. Gorilla's code,
model, data, and demo are available at https://gorilla.cs.berkeley.ed
POET: Training Neural Networks on Tiny Devices with Integrated Rematerialization and Paging
Fine-tuning models on edge devices like mobile phones would enable
privacy-preserving personalization over sensitive data. However, edge training
has historically been limited to relatively small models with simple
architectures because training is both memory and energy intensive. We present
POET, an algorithm to enable training large neural networks on memory-scarce
battery-operated edge devices. POET jointly optimizes the integrated search
search spaces of rematerialization and paging, two algorithms to reduce the
memory consumption of backpropagation. Given a memory budget and a run-time
constraint, we formulate a mixed-integer linear program (MILP) for
energy-optimal training. Our approach enables training significantly larger
models on embedded devices while reducing energy consumption while not
modifying mathematical correctness of backpropagation. We demonstrate that it
is possible to fine-tune both ResNet-18 and BERT within the memory constraints
of a Cortex-M class embedded device while outperforming current edge training
methods in energy efficiency. POET is an open-source project available at
https://github.com/ShishirPatil/poetComment: Proceedings of the 39th International Conference on Machine Learning
2022 (ICML 2022
Spin-orbit interaction in three-dimensionally bounded semiconductor nanostructures
The structural inversion asymmetry-induced spin-orbit interaction of
conduction band electrons in zinc-blende and wurtzite semiconductor structures
is analysed allowing for a three-dimensional (3D) character of the external
electric field and variation of the chemical composition. The interaction,
taking into account all remote bands perturbatively, is presented with two
contributions: a heterointerface term and a term caused by the external
electric field. They have generally comparable strength and can be written in a
unified manner only for 2D systems, where they can partially cancel each other.
For quantum wires and dots composed of wurtzite semiconductors new terms
appear, absent in zinc-blende structures, which acquire the standard Rashba
form in 2D systems.Comment: 18 pages, 1 figur
Recurrences in Driven Quantum Systems
We consider an initially bound quantum particle subject to an external
time-dependent field. When the external field is large, the particle shows a
tendency to repeatedly return to its initial state, irrespective of whether the
frequency of the field is sufficient for escape from the well. These
recurrences, which are absent in a classical calculation, arise from the system
evolving primarily like a free particle in the external field.Comment: 10 pages in RevTeX format, with three PS files appende
The Phantom Bounce: A New Oscillating Cosmology
An oscillating universe cycles through a series of expansions and
contractions. We propose a model in which ``phantom'' energy with
grows rapidly and dominates the late-time expanding phase. The universe's
energy density is so large that the effects of quantum gravity are important at
both the beginning and the end of each expansion (or contraction). The bounce
can be caused by high energy modifications to the Friedmann equation, which
make the cosmology nonsingular. The classic black hole overproduction of
oscillating universes is resolved due to their destruction by the phantom
energy.Comment: Four pages, one figure. V3: version to appear in JCA
A proposal for detecting the spin of a single electron in superfluid helium
The electron bubble in superfluid helium has two degrees of freedom that may
offer exceptionally low dissipation: the electron's spin and the bubble's
motion. If these degrees of freedom can be read out and controlled with
sufficient sensitivity, they would provide a novel platform for realizing a
range of quantum technologies and for exploring open questions in the physics
of superfluid helium. Here we propose a practical scheme for accomplishing this
by trapping an electron bubble inside a superfluid-filled opto-acoustic cavity.Comment: Main text: 5 pages, 5 figures. Supplement: 11 pages, 2 figures, 1
tabl
Inaccessible Singularities in Toral Cosmology
The familiar Bang/Crunch singularities of classical cosmology have recently
been augmented by new varieties: rips, sudden singularities, and so on. These
tend to be associated with final states. Here we consider an alternative
possibility for the initial state: a singularity which has the novel property
of being inaccessible to physically well-defined probes. These singularities
arise naturally in cosmologies with toral spatial sections.Comment: 10 pages, version to appear in Classical and Quantum Gravit
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