A quantum jump description for the non-Markovian dynamics of the spin-boson model

We derive a time-convolutionless master equation for the spin-boson model in the weak coupling limit. The temporarily negative decay rates in the master equation indicate short time memory effects in the dynamics which is explicitly revealed when the dynamics is studied using the non-Markovian jump description. The approach gives new insight into the memory effects influencing the spin dynamics and demonstrates, how for the spin-boson model the the co-operative action of different channels complicates the detection of memory effects in the dynamics.Comment: 9 pages, 6 figures, submitted to Proceedings of CEWQO200

Determination of the ΔS=1\Delta S = 1 weak Hamiltonian in the SU(4) chiral limit through topological zero-mode wave functions

A new method to determine the low-energy couplings of the $\Delta S=1$ weak Hamiltonian is presented. It relies on a matching of the topological poles in $1/m^2$ of three-point correlators of two pseudoscalar densities and a four-fermion operator, measured in lattice QCD, to the same observables computed in the $\epsilon$-regime of chiral perturbation theory. We test this method in a theory with a light charm quark, i.e. with an SU(4) flavour symmetry. Quenched numerical measurements are performed in a 2 fm box, and chiral perturbation theory predictions are worked out up to next-to-leading order. The matching of the two sides allows to determine the weak low-energy couplings in the SU(4) limit. We compare the results with a previous determination, based on three-point correlators containing two left-handed currents, and discuss the merits and drawbacks of the two procedures.Comment: 38 pages, 9 figure

Weak low-energy couplings from topological zero-mode wavefunctions

We discuss a new method to determine the low-energy couplings of the $\Delta S=1$ weak Hamiltonian in the $\epsilon$-regime. It relies on a matching of the topological poles in $1/m^2$ of three-point functions of two pseudoscalar densities and a four-fermion operator computed in lattice QCD, to the same observables in the Chiral Effective Theory. We present the results of a NLO computation in chiral perturbation theory of these correlation functions together with some preliminary numerical results.Comment: 7 pages. Contribution to Lattice 200

Thermodynamics of the QCD plasma and the large-N limit

The equilibrium thermodynamic properties of the SU(N) plasma at finite temperature are studied non-perturbatively in the large-N limit, via lattice simulations. We present high-precision numerical results for the pressure, trace of the energy-momentum tensor, energy density and entropy density of SU(N) Yang-Mills theories with N=3, 4, 5, 6 and 8 colors, in a temperature range from 0.8T_c to 3.4T_c (where T_c denotes the critical deconfinement temperature). The results, normalized according to the number of gluons, show a very mild dependence on N, supporting the idea that the dynamics of the strongly-interacting QCD plasma could admit a description based on large-N models. We compare our numerical data with general expectations about the thermal behavior of the deconfined gluon plasma and with various theoretical descriptions, including, in particular, the improved holographic QCD model recently proposed by Kiritsis and collaborators. We also comment on the relevance of an AdS/CFT description for the QCD plasma in a phenomenologically interesting temperature range where the system, while still strongly-coupled, approaches a `quasi-conformal' regime characterized by approximate scale invariance. Finally, we perform an extrapolation of our results to the N to $\infty$ limit.Comment: 1+38 pages, 13 eps figures; v2: added reference

Intensive big room process for co-creating value in legacy construction projects

In construction projects the changes and refinements of client requirements are often seen just as a disturbance causing additional costs. However, today clients' business needs evolve constantly and therefore changes in the project requirements are inevitable. Simultaneously, the increasing competition forces companies to minimise unproductive capital costs. Therefore there is an economical pressure to shorten the construction time and the design and construction will be even more concurrent than today. There is clearly potential value to be created for customer by terms of collaborative design process. Fira is an innovative Finnish company which has developed its interactive and customer centric Verstas process since 2009. Fira is using service logic as a guiding principle in the development of collaborative design processes, such as Intensive Big Room (IBR), which is a combination of Building Information Modelling (BIM) and further development of Integrated Concurrent Engineering (ICE ) and Big Room methodologies. The traditional project management methods are not efficient in managing late changes in customer's requirements. This article presents a new method combining collaborative design process, requirements management and IBR in a small sub-process - locking and ironmongery - in legacy construction project models. The sub-process was selected for the development of the method because it is a perfect example of the traditional fragmented process where efficient coordination between different participants and management of requirements are very difficult. However, the same principles can be applied to many other sub-processes too. The method combines service logic, value co-creation and use of IBR concept in a standard contract environment in a unique way which can give significant benefits to the companies able to adopt the presented concept in their business models. Using these methods Fira can now change its business model, differentiate with more attractive value proposal for customer, create more value than its competitors and capture value for securing its competitiveness in future

Meeting Global Cooling Demand with Photovoltaics during the 21st Century

Space conditioning, and cooling in particular, is a key factor in human productivity and well-being across the globe. During the 21st century, global cooling demand is expected to grow significantly due to the increase in wealth and population in sunny nations across the globe and the advance of global warming. The same locations that see high demand for cooling are also ideal for electricity generation via photovoltaics (PV). Despite the apparent synergy between cooling demand and PV generation, the potential of the cooling sector to sustain PV generation has not been assessed on a global scale. Here, we perform a global assessment of increased PV electricity adoption enabled by the residential cooling sector during the 21st century. Already today, utilizing PV production for cooling could facilitate an additional installed PV capacity of approximately 540 GW, more than the global PV capacity of today. Using established scenarios of population and income growth, as well as accounting for future global warming, we further project that the global residential cooling sector could sustain an added PV capacity between 20-200 GW each year for most of the 21st century, on par with the current global manufacturing capacity of 100 GW. Furthermore, we find that without storage, PV could directly power approximately 50% of cooling demand, and that this fraction is set to increase from 49% to 56% during the 21st century, as cooling demand grows in locations where PV and cooling have a higher synergy. With this geographic shift in demand, the potential of distributed storage also grows. We simulate that with a 1 m$^3$ water-based latent thermal storage per household, the fraction of cooling demand met with PV would increase from 55% to 70% during the century. These results show that the synergy between cooling and PV is notable and could significantly accelerate the growth of the global PV industry

Meeting Global Cooling Demand with Photovoltaics during the 21st Century

Space conditioning, and cooling in particular, is a key factor in human productivity and well-being across the globe. During the 21st century, global cooling demand is expected to grow significantly due to the increase in wealth and population in sunny nations across the globe and the advance of global warming. The same locations that see high demand for cooling are also ideal for electricity generation via photovoltaics (PV). Despite the apparent synergy between cooling demand and PV generation, the potential of the cooling sector to sustain PV generation has not been assessed on a global scale. Here, we perform a global assessment of increased PV electricity adoption enabled by the residential cooling sector during the 21st century. Already today, utilizing PV production for cooling could facilitate an additional installed PV capacity of approximately 540 GW, more than the global PV capacity of today. Using established scenarios of population and income growth, as well as accounting for future global warming, we further project that the global residential cooling sector could sustain an added PV capacity between 20-200 GW each year for most of the 21st century, on par with the current global manufacturing capacity of 100 GW. Furthermore, we find that without storage, PV could directly power approximately 50% of cooling demand, and that this fraction is set to increase from 49% to 56% during the 21st century, as cooling demand grows in locations where PV and cooling have a higher synergy. With this geographic shift in demand, the potential of distributed storage also grows. We simulate that with a 1 m$^3$ water-based latent thermal storage per household, the fraction of cooling demand met with PV would increase from 55% to 70% during the century. These results show that the synergy between cooling and PV is notable and could significantly accelerate the growth of the global PV industry

Remote polarization entanglement generation by local dephasing and frequency upconversion

We introduce a scheme for remote entanglement generation for the photon polarization. The technique is based on transferring the initial frequency correlations to specific polarization-frequency correlations by local dephasing and their subsequent removal by frequency up-conversion. On fundamental level, our theoretical results show how to create and transfer entanglement, to particles which never interact, by means of local operations. This possibility stems from the multi-path interference and its control in frequency space. For applications, the developed techniques and results allow for the remote generation of entanglement with distant parties without Bell state measurements and opens the perspective to probe frequency-frequency entanglement by measuring the polarization state of the photons.Comment: 8 page

Ultrafast spatiotemporal control of photocarriers in doped semiconductors

Control of the spatial and temporal dynamics of photoexcited charge carriers at the surfaces and interfaces of semiconducting materials is pertinent to many of modern technologies such as solar cells, photodetectors and other optoelectronic devices. In inhomogeneous materials such as nanostructured materials, spatial variations in carrier dynamics are inherent via the material design and accordingly allow for improvements in device performance e.g. transport of electrons from donor to acceptor regions in photovoltaic devices. On the other hand, one can also create spatial inhomogeneity in the carrier dynamics in homogeneous systems by using a non-uniform photoexcitation profile. This would have the advantage that the control of the carrier dynamics could be more flexible and not tied down to the fixed material design. In principle, photoexcitation even with a simple Gaussian beam could result in nontrivial inhomogeneous carrier dynamics within the full-width-half-maximum (FWHM) of the optical spot. However, in typical ultrafast spectroscopy measurements performed thus far, one averages out the photocarrier response over the excitation spot and spatial variations therein are inaccessible. In this thesis, we create nontrivial spatiotemporal dynamics of the photoexcited electrons in a homogeneous Zn-doped GaAs using the spatial intensity variation in a simple Gaussian photoexcitation beam. We image these dynamics using time-resolved photoemission electron microscopy (TR-PEEM) - a technique offering both high temporal and spatial resolutions. In particular, we demonstrate the spatial redistribution of the photoexcited electrons in two different regimes: (I) the early time delays where we control the vertical transport of electrons to the sample surface and (II) at long time delays where we manipulate the lateral distribution of the electrons along the sample surface.In the first study, we achieve spatial variations in the screening process of the intrinsic surface field, which influences the vertical drift of photoexcited electrons from the bulk to the sample surface. Combined with the occurrence of Auger recombination in regions of higher intensity, we see a depletion in the electron population at the center, with a gain just away from the center. We show control of these processes and how they affect the electron distribution on the sample surface in nontrivial ways. In the second study, we show that at long time delays the spatially varying screening process leads to the creation of lateral fields along the sample surface. These highly local and spatially varying lateral fields then act upon the photoexcited electrons, eventually pulling them apart into two distinct distributions. Using a simple model that explains the experimental data, we also show the possibility of generating near-arbitrary lateral fields and thus controlling electrons on the sample surface in more general ways. In conclusion, this thesis demonstrates the capability to create and control nontrivial spatiotemporal dynamics of the photoexcited electrons even in a homogeneous semiconductor by exploiting the intensity variation of an ultrafast light pulse. This capability could lead to a promising new handle for use in high-speed optoelectronic devices.Okinawa Institute of Science and Technology Graduate Universit