Duality and reciprocity of fluctuation-dissipation relations in conductors

By analogy with linear-response we formulate the duality and reciprocity properties of current and voltage fluctuations expressed by Nyquist relations including the intrinsic bandwidths of the respective fluctuations. For this purpose we individuate total-number and drift-velocity fluctuations of carriers inside a conductor as the microscopic sources of noise. The spectral densities at low frequency of the current and voltage fluctuations and the respective conductance and resistance are related in a mutual exclusive way to the corresponding noise-source. The macroscopic variance of current and voltage fluctuations are found to display a dual property via a plasma conductance that admits a reciprocal plasma resistance. Analogously, the microscopic noise-sources are found to obey a dual property and a reciprocity relation. The formulation is carried out in the frame of the grand canonical (for current noise) and canonical (for voltage noise) ensembles and results are derived which are valid for classical as well as for degenerate statistics including fractional exclusion statistics. The unifying theory so developed sheds new light on the microscopic interpretation of dissipation and fluctuation phenomena in conductors. In particular it is proven that, as a consequence of the Pauli principle, for Fermions non-vanishing single-carrier velocity fluctuations at zero temperature are responsible for diffusion but not for current noise, which vanishes in this limit.Comment: 5 pages, 1 figur

Carrier trapping in a quantum dash: optical signatures

We theoretically study the optical properties and the electronic structure of highly elongated quantum dots (quantum dashes) and show how geometrical fluctuations affect the excitonic spec- trum of the system. The dependence of the absorption intensities on the geometrical properties (depth and length) of the trapping center in a quantum dash is analyzed and the dependence of the degree of the linear polarization on these geometrical parameters is studied.Comment: 4 pages, 3 figure

Theory of the time-resolved Kerr rotation on trapped holes

We formulate a model of the time-resolved Kerr rotation experiment on a single hole in a semiconductor nanostructure (e.g., a quantum dot) or on an ensemble of trapped holes (e.g., in a quantum well) in a tilted magnetic field. We use a generic Markovian description of the hole and trion dephasing and focus on the interpretation of the time-resolved signal in terms of the microscopic evolution of the spin polarization. We show that the signal in an off-plane field contains components that reveal both the spin relaxation rate and the spin coherence dephasing rate. We derive analytical formulas for the hole spin polarization, which may be used to extract the two relevant rates by fitting to the measurement data.Comment: 13 pages, 7 figure

Formulation of the twisted-light–matter interaction at the phase singularity: The twisted-light gauge

Twisted light is light carrying orbital angular momentum. The profile of such a beam is a ring-like structure with a node at the beam axis, where a phase singularity exists. Due to the strong spatial inhomogeneity the mathematical description of twisted-light–matter interaction is non-trivial, in particular close to the phase singularity, where the commonly used dipole-moment approximation cannot be applied. In this paper we show that, if the handedness of circular polarization and the orbital angular momentum of the twisted-light beam have the same sign, a Hamiltonian similar to the dipole-moment approximation can be derived. However, if the signs differ, in general the magnetic parts of the light beam become of significant importance and an interaction Hamiltonian which only accounts for electric fields is inappropriate. We discuss the consequences of these findings for twisted-light excitation of a semiconductor nanostructures, e.g., a quantum dot, placed at the phase singularity.Fil: Quinteiro, Guillermo Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Kuhn, Tilmann. Westfalische Wilhelms Universitat; AlemaniaFil: Reiter, D. E.. Westfalische Wilhelms Universitat; Alemani

Light-hole transitions in quantum dots: Realizing full control by highly focused optical-vortex beams

An optical vortex is an inhomogeneous light beam having a phase singularity at its axis, where the intensity of the electric and/or magnetic field may vanish. Already well studied are the paraxial beams, which may carry well-defined values of spin (polarization σ) and orbital angular momenta; the orbital angular momentum per photon is given by the topological charge times the Planck constant. Here we study the light hole–to–conduction band transitions in a semiconductor quantum dot induced by a highly focused beam originating from a = 1 paraxial optical vortex. We find that at normal incidence the pulse will produce two distinct types of electron-hole pairs, depending on the relative signs of σ and . When sgn(σ) = sgn(), the pulse will create electron-hole pairs with band+spin and envelope angular momenta both equal to 1. In contrast, for sgn(σ) = sgn(), the electron-hole pairs will have neither band+spin nor envelope angular momenta. A tightly focused optical-vortex beam thus makes possible the creation of pairs that cannot be produced with plane waves at normal incidence. With the addition of co-propagating plane waves or switching techniques to change the charge both the band+spin and the envelope angular momenta of the pair wave function can be precisely controlled. We discuss possible applications in the field of spintronics that open up.Fil: Quinteiro, Guillermo Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universität Münster; AlemaniaFil: Kuhn, Tilmann. Universität Münster; Alemani

Design Development and Testing of Innovative Solar Control Facade Systems

Η παρούσα διδακτορική διατριβή ασχολείται με την αξιολόγηση των συστημάτων ελέγχου του ηλιαμού μέσω κριτηρίων απόδοσης και μετρήσεων. Παρουσιάζει επίσης τις μεθόδους για τη μαθηματικοφυσική μοντελοποίηση της αλληλεπίδρασης της ηλιακής ακτινοβολίας με το κέλυφος του κτιρίου, παρέχει μια επισκόπηση σχετικά με την εξέλιξη της τεχνολογίας των συστημάτων ελέγχου του ηλιασμού και εισάγει έξι νέα συστήματα ελέγχου που έχουν εφευρεθεί και αναπτυχθεί περαιτέρω με τη συνεισφορά του υποφαινόμενου. Αναπτύχθηκε μία νέα μεθοδολογία για μετρήσεις θερμιδομετρίας. Ο συγγραφέας με βάση τα αποτελέσματααυτών των μετρήσεων, συνέβαλε στον καθορισμό του νέου διεθνές προτύπουISO/CD 19467. Σημαντική ήταν ακόμη η συμβολή του στην καθιέρωση του «ενεργού g-value (ge)», το οποίο είναι το πρωτοχαρακτηριστικό που περιλαμβάνει όχι μόνο τις στατικές ιδιότητες του συστήματος ελέγχου, αλλά και τη λειτουργία / στρατηγική ελέγχου, η οποία είναι απαραίτητη για μια ρεαλιστική αξιολόγηση της απόδοσης. Ο παράγοντας geπου αναφέρεται στο κέντρο του υαλοπίνακα είναι ανεξάρτητοςγια συγκεκριμένο κτίριο. Εξαρτάται μόνο από τον προσανατολισμό και τη θέση και ως εκ τούτου μπορεί να χρησιμοποιηθεί για ένα γενικό χαρακτηρισμό της απόδοσης σε μια δεδομένη κλιματική ζώνη. Μια άλλη συνεισφορά είναι το νέο κριτήριο για την απόδοση των χρωμάτων των αντικειμένων στο χώρο, όπως φαίνονται από έναν εξωτερικό παρατηρητή (Rafromoutside).Αυτός ο παράγοντας απόδοσης δεν είχε ποσοτικοποιηθείέωςτώρα. Σημαντικές συνεισφορές έγιναν και όσον αφοράτα κριτήρια απόδοσης των συτημάτων ελέγχου ηλιασμού με ενσωματωμένα στο κτίριο φωτοβολταϊκών πλαισίων (BIPV)ή συτημάτων ελέγχου ηλιασμού με ενσωματωμένα στο κτίριο συστημάτων μετατροπής της ηλιακή θερμικής ενέργειας(BIST). Η μαθηματικοφυσική μοντελοποίηση της αλληλεπίδρασης της ηλιακής ακτινοβολίας με τα κτίρια συμπεριλαμβάνει τη μοντελοποίηση της μετάδοσης του φωτός της ημέρας, τη μοντελοποίηση των δευτερογενών θερμικών κερδών, ακόμη και τη μοντελοποίηση των φωτοβολταϊκών ή των συστημάτων μετατροπής της ηλιακής θερμικής ενέργειας. Η μεθοδολογία αυτή περιλαμβάνει λοιπόν τη μοντελοποίηση της απόδοσης τόσο του ίδιου του στοιχείου-συστατικού της πρόσοψης όσο καιτη μοντελοποίηση της απόδοσης του στοιχείου-συστατικούτης πρόσοψης στο σύστημα τουκτιρίου.This thesis deals with performance criteria and measurements for the evaluation of solar- control systems. It also presents methods for the mathematical-physical modeling of the interaction of solar irradiation with the building skin,it provides an overview on the state of the art of solar-control systems and it introduces six new solar-control systems which have been invented and further developed with contributions of the author.A new methodology for calorimetricg-value measurements has been developed. The author contributed to the new international standard ISO/CD 19467ong-value measurements on the basis of these results. Another major contribution is the introduction of the“eective g-valuege”,which is the rst product characteristic that includes not only the static properties of the solar-control system but also the operation/control strategy,which is essential for a realistic performance evalu- ation. The“center-of-glazing”propertyge is independent to the specic building. It only depends on the orientation and location and can therefore be used for general performance characterization within a given climatic zone. Another contribution is the new criterion for the colorrend erring of objects in the room, seen from an observer outside the building Rafromoutside.This performance aspect was not considered quantitatively until now.Contributions to perfor-mance criteria for BIPV or BIST solar-control systems with building integrated photovoltaic or solar thermal energy conversion have been made.The mathematical-physical modeling of the interaction of the solar radiation with the buildings kin ranges from modeling of the trans- mission of daylight and the modeling of secondary heat gains to the modeling of photovoltaic or solar thermal energy conversion. This includes the modeling of the performance of the facade component itself (modelingofge)and the modeling of the performance of the facade component in the building context