292 research outputs found
Verschraenkung versus Stosszahlansatz: Disappearance of the Thermodynamic Arrow in a High-Correlation Environment
The crucial role of ambient correlations in determining thermodynamic
behavior is established. A class of entangled states of two macroscopic systems
is constructed such that each component is in a state of thermal equilibrium at
a given temperature, and when the two are allowed to interact heat can flow
from the colder to the hotter system. A dilute gas model exhibiting this
behavior is presented. This reversal of the thermodynamic arrow is a
consequence of the entanglement between the two systems, a condition that is
opposite to molecular chaos and shown to be unlikely in a low-entropy
environment. By contrast, the second law is established by proving Clausius'
inequality in a low-entropy environment. These general results strongly support
the expectation, first expressed by Boltzmann and subsequently elaborated by
others, that the second law is an emergent phenomenon that requires a
low-entropy cosmological environment, one that can effectively function as an
ideal information sink.Comment: 4 pages, REVTeX
Is Integer Arithmetic Enough for Deep Learning Training?
The ever-increasing computational complexity of deep learning models makes
their training and deployment difficult on various cloud and edge platforms.
Replacing floating-point arithmetic with low-bit integer arithmetic is a
promising approach to save energy, memory footprint, and latency of deep
learning models. As such, quantization has attracted the attention of
researchers in recent years. However, using integer numbers to form a fully
functional integer training pipeline including forward pass, back-propagation,
and stochastic gradient descent is not studied in detail. Our empirical and
mathematical results reveal that integer arithmetic is enough to train deep
learning models. Unlike recent proposals, instead of quantization, we directly
switch the number representation of computations. Our novel training method
forms a fully integer training pipeline that does not change the trajectory of
the loss and accuracy compared to floating-point, nor does it need any special
hyper-parameter tuning, distribution adjustment, or gradient clipping. Our
experimental results show that our proposed method is effective in a wide
variety of tasks such as classification (including vision transformers), object
detection, and semantic segmentation
Entropic uncertainty relation for power-law wave packets
For the power-law quantum wave packet in configuration space, the variance of
the position observable may be divergent. Accordingly, the information-entropic
formulation of the uncertainty principle becomes more appropriate than the
Heisenberg-type formulation, since it involves only the finite quantities. It
is found that the total amount of entropic uncertainty converges to its lower
bound in the limit of a large value of the exponent.Comment: 10 pages, 3 figure
QED Corrections to Planck's Radiation Law and Photon Thermodynamics
Leading corrections to Planck's formula and photon thermodynamics arising
from the pair-mediated photon-photon interaction are calculated. This
interaction is attractive and causes an increase in occupation number for all
modes. Possible consequences, including the role of the cosmic photon gas in
structure formation, are considered.Comment: 15 pages, Revtex 3.
Integer Fine-tuning of Transformer-based Models
Transformer based models are used to achieve state-of-the-art performance on
various deep learning tasks. Since transformer-based models have large numbers
of parameters, fine-tuning them on downstream tasks is computationally
intensive and energy hungry. Automatic mixed-precision FP32/FP16 fine-tuning of
such models has been previously used to lower the compute resource
requirements. However, with the recent advances in the low-bit integer
back-propagation, it is possible to further reduce the computation and memory
foot-print. In this work, we explore a novel integer training method that uses
integer arithmetic for both forward propagation and gradient computation of
linear, convolutional, layer-norm, and embedding layers in transformer-based
models. Furthermore, we study the effect of various integer bit-widths to find
the minimum required bit-width for integer fine-tuning of transformer-based
models. We fine-tune BERT and ViT models on popular downstream tasks using
integer layers. We show that 16-bit integer models match the floating-point
baseline performance. Reducing the bit-width to 10, we observe 0.5 average
score drop. Finally, further reduction of the bit-width to 8 provides an
average score drop of 1.7 points
Stable ultrahigh-density magneto-optical recordings using introduced linear defects
The stability of data bits in magnetic recording media at ultrahigh densities
is compromised by thermal `flips' -- magnetic spin reversals -- of nano-sized
spin domains, which erase the stored information. Media that are magnetized
perpendicular to the plane of the film, such as ultrathin cobalt films or
multilayered structures, are more stable against thermal self-erasure than
conventional memory devices. In this context, magneto-optical memories seem
particularly promising for ultrahigh-density recording on portable disks, and
bit densities of 100 Gbit inch have been demonstrated using recent
advances in the bit writing and reading techniques. But the roughness and
mobility of the magnetic domain walls prevents closer packing of the magnetic
bits, and therefore presents a challenge to reaching even higher bit densities.
Here we report that the strain imposed by a linear defect in a magnetic thin
film can smooth rough domain walls over regions hundreds of micrometers in
size, and halt their motion. A scaling analysis of this process, based on the
generic physics of disorder-controlled elastic lines, points to a simple way by
which magnetic media might be prepared that can store data at densities in
excess of 1 Tbit inch.Comment: 5 pages, 4 figures, see also an article in TRN News at
http://www.trnmag.com/Stories/041801/Defects_boost_disc_capacity_041801.htm
Validity of the second law in nonextensive quantum thermodynamics
The second law of thermodynamics in nonextensive statistical mechanics is
discussed in the quantum regime. Making use of the convexity property of the
generalized relative entropy associated with the Tsallis entropy indexed by q,
Clausius' inequality is shown to hold in the range of q between zero and two.
This restriction on the range of the entropic index, q, is purely quantum
mechanical and there exists no upper bound of q for validity of the second law
in classical theory.Comment: 12 pages, no figure
Dynamical confinement in bosonized QCD2
In the bosonized version of two dimensional theories non trivial boundary
conditions (topology) play a crucial role. They are inevitable if one wants to
describe non singlet states. In abelian bosonization, color is the charge of a
topological current in terms of a non-linear meson field. We show that
confinement appears as the dynamical collapse of the topology associated with
its non trivial boundary conditions.Comment: 11 pages, figures not included, ftuv/92-
Coherent Schwinger Interaction from Darboux Transformation
The exactly solvable scalar-tensor potential of the four-component Dirac
equation has been obtained by the Darboux transformation method. The
constructed potential has been interpreted in terms of nucleon-nucleon and
Schwinger interactions of neutral particles with lattice sites during their
channeling Hamiltonians of a Schwinger type is obtained by means of the Darboux
transformation chain. The analitic structure of the Lyapunov function of
periodic continuation for each of the Hamiltonians of the family is considered.Comment: 12 pages, Latex, six figures; six sections, one figure adde
PET/MRI: a novel hybrid imaging technique. Major clinical indications and preliminary experience in Brazil
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