9,459 research outputs found
Evaluating Asymmetric Multicore Systems-on-Chip using Iso-Metrics
The end of Dennard scaling has pushed power consumption into a first order
concern for current systems, on par with performance. As a result,
near-threshold voltage computing (NTVC) has been proposed as a potential means
to tackle the limited cooling capacity of CMOS technology. Hardware operating
in NTV consumes significantly less power, at the cost of lower frequency, and
thus reduced performance, as well as increased error rates. In this paper, we
investigate if a low-power systems-on-chip, consisting of ARM's asymmetric
big.LITTLE technology, can be an alternative to conventional high performance
multicore processors in terms of power/energy in an unreliable scenario. For
our study, we use the Conjugate Gradient solver, an algorithm representative of
the computations performed by a large range of scientific and engineering
codes.Comment: Presented at HiPEAC EEHCO '15, 6 page
Entanglement loss in molecular quantum-dot qubits due to interaction with the environment
We study quantum entanglement loss due to environmental interaction in a
condensed matter system with a complex geometry relevant to recent proposals
for computing with single electrons at the nanoscale. We consider a system
consisting of two qubits, each realized by an electron in a double quantum dot,
which are initially in an entangled Bell state. The qubits are widely separated
and each interacts with its own environment. The environment for each is
modeled by surrounding double quantum dots placed at random positions with
random orientations. We calculate the unitary evolution of the joint system and
environment. The global state remains pure throughout. We examine the time
dependence of the expectation value of the bipartite Clauser-Horne-Shimony-Holt
(CHSH) and Brukner-Paunkovi\'c-Rudolph-Vedral (BPRV) Bell operators and explore
the emergence of correlations consistent with local realism. Though the details
of this transition depend on the specific environmental geometry, we show how
the results can be mapped on to a universal behavior with appropriate scaling.
We determine the relevant disentanglement times based on realistic physical
parameters for molecular double-dots.Comment: 14 pages, 3 figure
The Unruh Quantum Otto Engine
We introduce a quantum heat engine performing an Otto cycle by using the
thermal properties of the quantum vacuum. Since Hawking and Unruh, it has been
established that the vacuum space, either near a black hole or for an
accelerated observer, behaves as a bath of thermal radiation. In this work, we
present a fully quantum Otto cycle, which relies on the Unruh effect for a
single quantum bit (qubit) in contact with quantum vacuum fluctuations. By
using the notions of quantum thermodynamics and perturbation theory we obtain
that the quantum vacuum can exchange heat and produce work on the qubit.
Moreover, we obtain the efficiency and derive the conditions to have both a
thermodynamic and a kinematic cycle in terms of the initial populations of the
excited state, which define a range of allowed accelerations for the Unruh
engine.Comment: 31 pages, 11 figure
Entry regulation and business start-ups : evidence from Mexico
The authors estimate the effect on business start-ups of a program that significantly speeds up firm registration procedures. The program was implemented in Mexico in different municipalities at different dates. Authors estimates suggest that new start-ups increased by about 4 percent in eligible industries, and the authors present evidence that this is a causal effect. Most of the effect is temporary, concentrated in the first 10 months after implementation. The effect is robust to several specifications of the benchmark control group time trends. The authors find that the program was more effective in municipalities with less corruption and cheaper additional procedures.Corporate Law,Microfinance,Regional Governance,Urban Governance and Management,Urban Partnerships&Poverty
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