1,234 research outputs found
Localization by Dissipative Disorder: a Deterministic Approach to Position Measurements
We propose an approach to position measurements based on the hypothesis that
the action of a position detector on a quantum system can be effectively
described by a dissipative disordered potential. We show that such kind of
potential is able, via the dissipation-induced Anderson localization, to
contemporary localize the wavefunction of the system and to dissipate
information to modes bounded to the detector. By imposing a diabaticity
condition we demonstrate that the dissipative dynamics between the modes of the
system leads to a localized energy exchange between the detector and the rest
of the environment -the "click" of the detector- thus providing a complete
deterministic description of a position measurement. We finally numerically
demonstrate that our approach is consistent with the Born probability rule
Dynamical instability and dispersion management of an attractive condensate in an optical lattice
We investigate the stability of an attractive Bose-Einstein condensate in a
moving 1D optical lattice in the presence of transverse confinement. By means
of a Bogoliubov linear stability analysis we find that the system is
dynamically unstable for low quasimomenta and becomes stable near the band
edge, in a specular fashion with respect to the repulsive case. For low
interactions the instability occurs via long wavelength excitations that are
not sufficient for spoiling the condensate coherence, producing instead an
oscillating density pattern both in real and momentum space. This behaviour is
illustrated by simulations for the expansion of the condensate in a moving
lattice.Comment: 5 pages, 4 figure
Separation and recovery of materials from scrap printed circuit boards
Printed circuit boards from waste computers, televisions, and mobile phones were pyrolysed in a fixed bed reactor with the aim of separating and recovering the organic and metallic materials. A selection of printed circuit boards from each of the three waste classes was pyrolysed at 800°C and the pyrolysis products were analysed using GC-FID, GC-TCD, GC-MS, GC-ECD, ICP-MS, and SEM-EDX. The pyrolysis oils contained high concentrations of phenol, 4-(1-methylethyl)phenol, and p-hydroxyphenol, as well as bisphenol A, tetrabromobisphenol A, methyl phenols, and bromophenols. The pyrolysis oils also contained significant concentrations of organo – phosphate compounds and a number of tetrabromobisphenol A pyrolysis products were also identified.
The pyrolysis residues were very fragile and the organic, glass fibre, and metallic fractions could easily be separated and the electrical components could easily be removed from the remains of the printed circuit boards. The ash in the residue mainly consisted of copper, calcium, iron, nickel, zinc, and aluminium, as well as lower concentrations of valuable metals such as gallium, bismuth, silver, and gold, silver was present in particularly high concentrations. Many other metals were also identified in the ash by ICP-MS and SEM EDX. The pyrolysis gases mainly consisted of CO2 and CO but all of the C1 – C4 alkanes and alkenes were present, as were some inorganic halogens
Endoscopic imaging of quantum gases through a fiber bundle
We use a coherent fiber bundle to demonstrate the endoscopic absorption
imaging of quantum gases. We show that the fiber bundle introduces spurious
noise in the picture mainly due to the strong core-to-core coupling. By direct
comparison with free-space pictures, we observe that there is a maximum column
density that can be reliably measured using our fiber bundle, and we derive a
simple criterion to estimate it. We demonstrate that taking care of not
exceeding such maximum, we can retrieve exact quantitative information about
the atomic system, making this technique appealing for systems requiring
isolation form the environment
Ma che bel castello, marcondirondirondello! Progettazione di una scuola dell'infanzia a S.Frediano a Settimo, Comune di Cascina (Pisa)
La presente tesi tratta della progettazione architettonica di una scuola dell’infanzia a S.Frediano a Settimo nel Comune di Cascina (Pisa), con attenzione al DM 18/12/1975 (Norme tecniche aggiornate relative all'edilizia scolastica, ivi compresi gli indici di funzionalità didattica, edilizia ed urbanistica, da osservarsi nella esecuzione di opere di edilizia scolastica). Vi è stato un particolare studio per quanto riguarda i materiali, il cromatismo e la scelta delle essenze per l’area adibita a giardino. Le scelte progettuali hanno puntato l’attenzione su forme e simbologie ricorrenti nella vita del bambino. L’utilizzo del colore è stato un aspetto fondamentale dello studio fatto. A seguito del colloquio con alcuni insegnanti, vi è stata una accurata attenzione alla funzionalità della distribuzione degli spazi sia interni che esterni. I disegni di alcuni bambini sono stati il punto di partenza per la progettazione del complesso in quanto è stato chiesto loro di rappresentare la propria scuola dei sogni
Vortex conveyor belt for matter-wave coherent splitting and interferometry
We numerically study a matter wave interferometer realized by splitting a
trapped Bose-Einstein condensate with phase imprinting. We show that a simple
step-like imprinting pattern rapidly decays into a string of vortices that can
generate opposite velocities on the two halves of the condensate. We first
study in detail the splitting and launching effect of these vortex structures,
whose functioning resembles the one of a conveyor belt, and we show that the
initial exit velocity along the vortex conveyor belt can be controlled
continuously by adjusting the vortex distance. We finally characterize the
complete interferometric sequence, demonstrating how the phase of the resulting
interference fringe can be used to measure an external acceleration. The
proposed scheme has the potential to be developed into compact and high
precision accelerometers
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