1,279 research outputs found
Non-classical Rotational Inertia in a Two-dimensional Bosonic Solid Containing Grain Boundaries
We study the occurrence of non-classical rotational inertia (NCRI) arising
from superfluidity along grain boundaries in a two-dimensional bosonic system.
We make use of a standard mapping between the zero-temperature properties of
this system and the statistical mechanics of interacting vortex lines in the
mixed phase of a type-II superconductor. In the mapping, the liquid phase of
the vortex system corresponds to the superfluid bosonic phase. We consider
numerically obtained polycrystalline configurations of the vortex lines in
which the microcrystals are separated by liquid-like grain boundary regions
which widen as the vortex system temperature increases. The NCRI of the
corresponding zero-temperature bosonic systems can then be numerically
evaluated by solving the equations of superfluid hydrodynamics in the channels
near the grain boundaries. We find that the NCRI increases very abruptly as the
liquid regions in the vortex system (equivalently, superfluid regions in the
bosonic system) form a connected, system-spannig structure with one or more
closed loops. The implications of these results for experimentally observed
supersolid phenomena are discussed.Comment: Ten pages, including figure
Optimal Cloning of Pure States, Judging Single Clones
We consider quantum devices for turning a finite number N of d-level quantum
systems in the same unknown pure state \sigma into M>N systems of the same
kind, in an approximation of the M-fold tensor product of the state \sigma. In
a previous paper it was shown that this problem has a unique optimal solution,
when the quality of the output is judged by arbitrary measurements, involving
also the correlations between the clones. We show in this paper, that if the
quality judgement is based solely on measurements of single output clones,
there is again a unique optimal cloning device, which coincides with the one
found previously.Comment: 16 Pages, REVTe
A complete design path for the layout of flexible macros
XIV+172hlm.;24c
Correlated microtiming deviations in jazz and rock music
Musical rhythms performed by humans typically show temporal fluctuations.
While they have been characterized in simple rhythmic tasks, it is an open
question what is the nature of temporal fluctuations, when several musicians
perform music jointly in all its natural complexity. To study such fluctuations
in over 100 original jazz and rock/pop recordings played with and without
metronome we developed a semi-automated workflow allowing the extraction of
cymbal beat onsets with millisecond precision. Analyzing the inter-beat
interval (IBI) time series revealed evidence for two long-range correlated
processes characterized by power laws in the IBI power spectral densities. One
process dominates on short timescales ( beats) and reflects microtiming
variability in the generation of single beats. The other dominates on longer
timescales and reflects slow tempo variations. Whereas the latter did not show
differences between musical genres (jazz vs. rock/pop), the process on short
timescales showed higher variability for jazz recordings, indicating that jazz
makes stronger use of microtiming fluctuations within a measure than rock/pop.
Our results elucidate principles of rhythmic performance and can inspire
algorithms for artificial music generation. By studying microtiming
fluctuations in original music recordings, we bridge the gap between
minimalistic tapping paradigms and expressive rhythmic performances
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SLAM : an automated structure to layout synthesis system
SLAM is a structure to layout synthesis system. It incorporates parameterisable bit-sliced and glue-logic generators to produce high density layout. In this paper, we describe a sliced layout architecture and SLAM system. In addition, we present partitioning algorithms for generating the floorplan for such an architecture. The algorithms partition the netlist into component sets best suited for different layout styles such as bit-sliced or strip-oriented logic. Each group is partitioned further into clusters to achieve better area utilization. Several experiments demonstrate that highly dense layouts can be achieved by using these algorithms with the sliced layout architecture
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