Kitaev chains with long-range pairing

We propose and analyze a generalization of the Kitaev chain for fermions with long-range $p$-wave pairing, which decays with distance as a power-law with exponent $\alpha$. Using the integrability of the model, we demonstrate the existence of two types of gapped regimes, where correlation functions decay exponentially at short range and algebraically at long range ($\alpha > 1$) or purely algebraically ($\alpha < 1$). Most interestingly, along the critical lines, long-range pairing is found to break conformal symmetry for sufficiently small $\alpha$. This is accompanied by a violation of the area law for the entanglement entropy in large parts of the phase diagram in the presence of a gap, and can be detected via the dynamics of entanglement following a quench. Some of these features may be relevant for current experiments with cold atomic ions.Comment: 5+3 pages, 4+2 figure

Energy saving in typical architecture: The flow energy in traditional solutions in a sustainable perspective

Quick urbanization increment causes a few difficult problems, such as social assessment, more energy demands, and pollution increase. A positive factor for a city is the concentration of energy requests. On the other hand, urbanization trend is going to fragmentation of settlements, with a consequent expansion of the energy distribution networks but also an increase of the energy wasted. Each building needs some of the total energy distributed in the city. Energy needs can be grouped into four essential parameters: construction, heating, electricity, and water. How were these four parameters satisfied in the XIX century, before the industrial revolution? In those days' energy requirement wasn't so high and could be supplied with basic energy production technology. The knowledge of appropriate building technology (project), the use of (energy saving) materials, with a low and punctual heating system (fireplace, stove) or passive refreshment all intervened in this process. These requirements were achieved in each country using building plans studied to face different weather conditions with different architectural typology and with human effort and time (work-energy). This paper analyses an energy balance in a single typical building in the center of Italy, describing the energy flow that will show the logical and technical solution for "energy-saving". Old buildings (before the introduction of "building-plant") were always designed and built with an energy-saving concern. This article wants to propose the study of a typical building in which are used only low-energy systems to meet all the comfort requirements, to demonstrate that it is not necessary to use high-energy technology. This is how architecture urbanization studies and implementation can be used to reduce high-energy production needs. © 2019 Author(s)

Building performance monitoring: From in-situ measurement to regression-based approaches

Simple and robust data analysis methodologies are crucial to learn insights from measured data and reduce the performance gap in building stock. For this reason, continuous performance monitoring should become a more diffuse practice in order to improve our design and operation strategies for the future. The research presented aims to highlight potential links between experimental approaches for test-facilities and methods and tools used for continuous performance monitoring, at the state of the art. In particular, we explore the relation between ISO 9869:2014 method for in-situ measurement of thermal transmittance (U) and regression-based monitoring approaches, such as co-heating test and energy signature, for heat load coefficient (HLC) and solar aperture (gA) estimation. In particular, we highlight the robustness and scalability of these monitoring techniques, considering relevant issues in current integrated engineer design perspective. These issues include, among others, the necessity of limiting the number of a sensors to be installed in buildings, the possibility of employing both experimental and real operation data and, finally, the possibility to automate and perform monitoring at multiple scales, from single components, to individual buildings, to building stock and cities

Energy Transition at Home: A Survey on the Data and Practices That Lead to a Change in Household Energy Behavior

Since energy transition depends significantly on reducing the built environment’s energy needs, many regulations and incentives have been implemented globally over the last three decades. Despite some positive results, many scholars suggest that households’ behavioral change could greatly accelerate progress. People’s levels of awareness and willingness to change, as well as the provision of feedback technologies, are important factors affecting the process. In spite of the extent of this body of literature, household consumption keeps rising. Our thesis is that the subject has been investigated without considering some important correlations among factors. Therefore, this study developed a survey to investigate actual consumers’ perspectives on the topic by combining people’s awareness of energy use, interaction with metering devices, and user motivation into a coherent framework. A testing session involving 500 people was held as a validation phase for a future large-scale launch of the questionnaire. The test yielded some early outcomes on how people become more interested in changing as they gain more knowledge and are offered suggestions. However, despite their supposedly advanced knowledge as educators and students, the sample’s level of awareness was low, suggesting that a more user-centered approach is needed for wide-scale progress

Static and dynamic thermal properties of construction components: A comparison in idealized and experimental conditions using lumped parameter models

The U values assumptions for construction components represent a significant source of uncertainty when estimating the energy performance of buildings. This uncertainty affects decision-making processes in multiple ways, from policy making to design of new and refurbished buildings. The correct estimation of both static (e.g. thermal transmittance) and dynamic thermal properties is crucial for quality assurance in building performance assessment. Further, while today many sophisticated simulators are available for building performance modelling, lumped parameter models can help reducing computational time for parametric simulation or optimization and enable inverse estimation of lumped thermal characteristics. A lumped parameter approach for construction components is proposed, for example, by the ISO 52016-1:2017 norm, introducing simplifications that are intrinsically dependent on component's stratigraphy. This approach complements ISO 13786:2017 norm method, which is limited to steady-state periodic temperature and heat flux boundary conditions. In this research we consider these two different approaches, detailed and lumped modelling, comparing them first in idealized conditions and then in experimental conditions to analyse the robustness of methods

The use of building performance simulation to support architectural design: a case study

Abstract Considering the complex interaction between energy performance, lighting, acoustic and thermal comfort in contemporary design, building performance simulation [BPS] shall play a key role in addressing decision making process and technical choices towards optimized configuration during the whole design phase. The paper reports the outcomes of a case study – performed in the framework of Ma Final Design Lab at the Department of Architecture, University of Bologna – where BPS was adopted from the very beginning as a tool to support the design process from the concept validation to the final architectural configuration to fit with passive house standards

Topological massive Dirac edge modes and long-range superconducting Hamiltonians

We discover novel topological effects in the one-dimensional Kitaev chain modified by long-range Hamiltonian deformations in the hopping and pairing terms. This class of models display symmetry-protected topological order measured by the Berry/Zak phase of the lower-band eigenvector and the winding number of the Hamiltonians. For exponentially decaying hopping amplitudes, the topological sector can be significantly augmented as the penetration length increases, something experimentally achievable. For power-law decaying superconducting pairings, the massless Majorana modes at the edges get paired together into a massive nonlocal Dirac fermion localized at both edges of the chain: a new topological quasiparticle that we call topological massive Dirac fermion. This topological phase has fractional topological numbers as a consequence of the long-range couplings. Possible applications to current experimental setups and topological quantum computation are also discussed

Adaptive Bayesian phase estimation for quantum error correcting codes

Realisation of experiments even on small and medium-scale quantum computers requires an optimisation of several parameters to achieve high-fidelity operations. As the size of the quantum register increases, the characterisation of quantum states becomes more difficult since the number of parameters to be measured grows as well and finding efficient observables in order to estimate the parameters of the model becomes a crucial task. Here we propose a method relying on application of Bayesian inference that can be used to determine systematic, unknown phase shifts of multi-qubit states. This method offers important advantages as compared to Ramsey-type protocols. First, application of Bayesian inference allows the selection of an adaptive basis for the measurements which yields the optimal amount of information about the phase shifts of the state. Secondly, this method can process the outcomes of different observables at the same time. This leads to a substantial decrease in the resources needed for the estimation of phases, speeding up the state characterisation and optimisation in experimental implementations. The proposed Bayesian inference method can be applied in various physical platforms that are currently used as quantum processors

Noise controlling by means of intensity of acoustic radiation measurements

Noise control in working places often involves the design of acoustic treatment of enclosures and the design of proper devices able to reduce vibration of surfaces in machinery and structural borne propagation. However, in order to optimize the efficiency of the treatment, it would be very useful to properly relate the vibration with total sound emission. From a general point of view, it is quite important to determine the relation between vibration surfaces and total sound (or noise) emission. The same problem could be also studied for several other sources, such as loudspeakers or musical instruments. We employ the Intensity of Acoustic Radiation (IAR), a novel, corresponding parameter introduced recently, that relates modal analysis with sound production. This parameter is defined as the space-averaged amplitude of cross-spectrum between sound pressure caused by the movement of the vibrating surface and the velocity of the vibration of the surface itself. To measure IAR, an omnidirectional microphone is placed in a fixed position at a short distance over the surface, while an accelerometer is mounted at the same points utilized during modal analysis. IAR showing a very high correlation between Frequency Response Function (FRF) and sound production of the surfaces is, therefore, able to describe the relationship between vibration and noise emission

An exergy metric for building performance evaluation

Building energy performance evaluation is a key action to comply with EU Directive on Energy Efficiency in Buildings as well as the regulations' adoption at National level for Energy Certificates and Label assignments. As a matter of fact, a comprehensive and detailed analysis of heat exchange in existing buildings and new ones is still missing due to the complexity of established procedures and huge amount of buildings to assess. For this purpose, an exergy audit considering the designed indoor temperature, the building envelope behavior and heating production and distribution systems allows computing the building performance with more detail by including the exergy consumption of the whole system. This method could provide more detailed calculations in the summer season even by simplifying the shadows and natural ventilation effects on the cooling demand due to their contribution to the amount of variables and complexity. The method here described starts from the LowEX tool developed in the IEA ECBCS Annex 37 framework to elaborate a final new metric. Accounting for the energy conservation principle, the total amount of exergy exchanged by the building is obtained as the addition of the exergy exchanged in each sub-system, i.e. the building envelope, the energy generation and the distribution system. Finally, the efficiency of the system could be calculated, comparing the amount of energy consumption and exergy exchanges. By using the exergy approach, other indicators could be analyzed, i.e Tonne of Oil Equivalent (TOE), CO2 emission and fossil fuel consumption. Among those ones, the ratio between TOE produced by the heating system and the exergy exchanged by the system represents the new exergy parameter. This latter is tested on an existing building as case study