31 research outputs found
Modelling the effect of the Ecodesign and Labelling directives – Bottom-up analysis of EU-27 residential electricity use
The Ecodesign and Labelling directives are key policy measures to increase energy efficiency in Europe. In view of the extension of Ecodesign and Labelling to further products as well as the revision of the current implementing directives, it is essential to evaluate the potential energy savings, takin g into account different paths of technological development and diffusion. Our study uses bottom - up modelling to evaluate the long - term saving potentials of Ecodesign and Label ling for residential appliances (including large appliances, cooking and ICT), lighting and air conditioning. The household end - uses that are affected by the legislation are implemented in the model in a disaggregated way. The model is designed as a vintage stock approach and based on the simulation of consumer activities as well as technological trajectories. We model the electricity demand of household end - uses in the EU - 27 by country and compare various scenarios. Our Reference Scenario reflects the electricity demand of household end - uses without any policy measures implemented after 2008. Our current Policy Scenario includes all implementing directives that are currently in force and assumes that the sensitivity of consumers to the total cost of ownership remains at the currently witnessed level. Finally, our LLCC Scenario explores the potential energy savings assuming that consumers choose the economically favourable options considering the total cost of ownership
Atom Counting in Expanding Ultracold Clouds
We study the counting statistics of ultracold bosonic atoms that are released
from an optical lattice. We show that the counting probability distribution of
the atoms collected at a detector located far away from the optical lattice can
be used as a method to infer the properties of the initially trapped states. We
consider initial superfluid and insulating states with different occupation
patterns. We analyze how the correlations between the initially trapped modes
that develop during the expansion in the gravitational field are reflected in
the counting distribution. We find that for detectors that are large compared
to the size of the expanded wave function, the long-range correlations of the
initial states can be distinguished by observing the counting statistics. We
consider counting at one detector, as well as the joint probability
distribution of counting particles at two detectors. We show that using
detectors that are small compared to the size of the expanded wave function,
insulating states with different occupation patterns, as well as supersolid
states with different density distributions can be distinguished
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Fermion- and Spin-Counting in Strongly Correlated Systems
We apply the atom counting theory to strongly correlated Fermi systems and spin models, which can be realized with ultracold atoms. The counting distributions are typically sub-Poissonian and remain smooth at quantum phase transitions, but their moments exhibit critical behavior, and characterize quantum statistical properties of the system. Moreover, more detailed characterizations are obtained with experimentally feasible spatially resolved counting distributions.Physic
Fermion- and spin-counting in strongly correlated systems in and out of thermal equilibrium
Atom counting theory can be used to study the role of thermal noise in
quantum phase transitions and to monitor the dynamics of a quantum system. We
illustrate this for a strongly correlated fermionic system, which is equivalent
to an anisotropic quantum XY chain in a transverse field, and can be realized
with cold fermionic atoms in an optical lattice. We analyze the counting
statistics across the phase diagram in the presence of thermal fluctuations,
and during its thermalization when the system is coupled to a heat bath. At
zero temperature, the quantum phase transition is reflected in the cumulants of
the counting distribution. We find that the signatures of the crossover remain
visible at low temperature and are obscured with increasing thermal
fluctuations. We find that the same quantities may be used to scan the dynamics
during the thermalization of the system.Comment: 10 pages, 7 figure
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Fermion and spin counting in strongly correlated systems
We apply the atom counting theory to strongly correlated Fermi systems and spin models, which can be realized with ultracold atoms. The counting distributions are typically sub-Poissonian and remain smooth at quantum phase transitions, but their moments exhibit critical behavior, and characterize quantum statistical properties of the system. Moreover, more detailed characterizations are obtained with experimentally feasible spatially resolved counting distributions.Physic
Trapped ion chain as a neural network
We demonstrate the possibility of realizing a neural network in a chain of
trapped ions with induced long range interactions. Such models permit to store
information distributed over the whole system. The storage capacity of such
network, which depends on the phonon spectrum of the system, can be controlled
by changing the external trapping potential and/or by applying longitudinal
local magnetic fields. The system properties suggest the possibility of
implementing robust distributed realizations of quantum logic.Comment: 4 pages, 3 figure
Error-Resistant Distributed Quantum Computation in Trapped Ion Chain
We consider experimentally feasible chains of trapped ions with pseudo-spin
1/2, and find models that can potentially be used to implement error-resistant
quantum computation. Similar in spirit to classical neural networks, the
error-resistance of the system is achieved by encoding the qubits distributed
over the whole system. We therefore call our system a ''quantum neural
network'', and present a ''quantum neural network model of quantum
computation''. Qubits are encoded in a few quasi-degenerated low energy levels
of the whole system, separated by a large gap from the excited states, and
large energy barriers between themselves. We investigate protocols for
implementing a universal set of quantum logic gates in the system, by adiabatic
passage of a few low-lying energy levels of the whole system. Naturally
appearing and potentially dangerous distributed noise in the system leaves the
fidelity of the computation virtually unchanged, if it is not too strong. The
computation is also naturally resilient to local perturbations of the spins.Comment: 10 pages, 7 figures, RevTeX4; v2: another noise model analysed,
published versio
Particle Counting Statistics of Time and Space Dependent Fields
The counting statistics give insight into the properties of quantum states of
light and other quantum states of matter such as ultracold atoms or electrons.
The theoretical description of photon counting was derived in the 1960s and was
extended to massive particles more recently. Typically, the interaction between
each particle and the detector is assumed to be limited to short time
intervals, and the probability of counting particles in one interval is
independent of the measurements in previous intervals. There has been some
effort to describe particle counting as a continuous measurement, where the
detector and the field to be counted interact continuously. However, no general
formula applicable to any time and space dependent field has been derived so
far. In our work, we derive a fully time and space dependent description of the
counting process for linear quantum many-body systems, taking into account the
back-action of the detector on the field. We apply our formalism to an
expanding Bose-Einstein condensate of ultracold atoms, and show that it
describes the process correctly, whereas the standard approach gives unphysical
results in some limits. The example illustrates that in certain situations, the
back-action of the detector cannot be neglected and has to be included in the
description
Complex systems for quantum technologies
Postprint (published version
Building a Common Support Framework in Differing Realities—Conditions for Renewable Energy Communities in Germany and Bulgaria
The revised EU Renewable Energy Directive first introduced renewable energy communities into the EU policy framework and requires Member States to implement a support framework for them. Given the broad scientific evidence showing the benefits of community energy for a just energy transition, a successful implementation across all Member States is essential. However, the preconditions for developing support frameworks differ largely between EU nations, as some countries have long-term experiences with supporting renewable energy communities (i.e., Germany and Denmark), while in other Member States, renewable energy communities are notably non-existent (i.e., Eastern European nations). With the purpose of providing scientific evidence to support the development of a policy framework for renewable energy communities in Eastern European Member States, this article compares key factors for the development of such communities in Bulgaria and Germany, combining a literature review with expert interviews to collect primary information on Bulgaria. A country analysis puts these factors into the contexts of both countries, while a cross-country comparison demonstrates that there are significant gaps in the support framework of Bulgaria, although these gaps are, to a lesser extent, also present in Germany. We discuss these shortcomings, derive policy recommendations and identify further research needs