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Continuous cavity QED with an atomic beam
Full text linkAtoms coupled to cavities provide an exciting playground for the study of fundamental interactions of atoms mediated through a common channel. Many of the applications of cavity QED and cold-atom experiments more broadly, suffer from limitations caused by the transient nature of an atomic loading cycle. The development of continuous operation schemes is necessary to push these systems to the next level of performance. Here we present a machine designed to produce a continuous flux of collimated atoms that traverse an optical cavity. The atom-light interaction is enhanced by a fast-decaying cavity optimal for studying phenomena where atomic properties dominate. We demonstrate the transition to a collective strong-coupling regime heralded by a normal-mode splitting. We observe a second phase with a binary normal-mode splitting born from an offset in the mean velocity of the atoms. Inverting the atomic ensemble in the collective strong-coupling regime, we measure continuous optical gain. This work sets the stage for studying threshold conditions for continuous collective phenomena, such as continuous superradiant lasing
Enhancing Surface Charge Density of Graphene Oxide Membranes through Al(OH)4- Anion Incorporation for Osmotic Energy Conversion
Full text linkGraphene oxide (GO) has been extensively studied for fabricating ion exchange membranes. This material is of interest due to its surface-governed charge which, combined with the interlayer distance between the GO flakes stack, offers ion selectivity. However, obtaining high-performing membranes with high ion selectivity and low ionic resistance remains challenging. To address this issue, Al(OH)4− anions are incorporated into graphene oxide membranes to increase their spontaneous negative surface charge. The anions are successfully formed and encapsulated through a reaction with the alumina support under alkaline conditions during the membrane fabrication. A modeling of the system proves the anchoring of the Al(OH)4− anions within the GO matrix. The incorporation of these anions significantly improves the permselectivity and reduces the ionic resistance, reaching approximately 95% and 2 Ω cm2, respectively. The GO-modified membranes also present mono-valent selectivity, which can boost reverse electrodialysis power densities
Earthquakelike dynamics in ultrathin magnetic films
Full text linkWe study the motion of a domain wall on an ultrathin magnetic film using the magneto-optical Kerr effect (MOKE). Our measurements were conducted at magnetic fields approximately 2% of the depinning field where the wall creeps only via thermal activation over the pinning centers present in the sample. Our results show that this creep dynamics is highly intermittent and correlated. A localized instability triggers a cascade, akin to aftershocks following a large earthquake, where the pinned wall undergoes large reorganizations in a compact active region for a few seconds. The analysis of their scale-free statistics enables us to solve an intricate, longstanding problem: thermal avalanches exist in the creep regime and they are depinning-like even for very low magnetic field. Moreover, we show that their sizes and shapes belong to the depinning quenched Kardar-ParisiZhang universality class
Gravitational and Coriolis forces in crystal neutron interferometry. II. Numerical simulations
Full text linkPrevious studies have proven that neutron interference using split-crystal interferometers is possible. This proof paves the way for extended arm separation and length, opening the doors to new experiments exploring quantum mechanics and gravity. In a previous publication, we took a closer look at how gravitational and Coriolis forces affect dynamical diffraction in crystal interferometry. This paper uses the formalism developed, which allows for extended capabilities in studying the interferometer operation, to investigate numerically the contributions to the neutron phase of geometrical aberrations and dynamical diffraction. In addition, this work explores an alternative geometry, with the interferometer operated vertically, to determine the gravitationally induced quantum-mechanical phase independently of the dynamical diffraction and self-weight bending of the interferometer
Hybrid Comparison between INRIM and IMBIH of air temperature sensors calibrations in the range -20 °C to 60 °C. In the framework of the project EURAMET P1586
No full textL’INRIM e IMBIH hanno organizzato un confronto ibrido bilaterale sulle tarature di strumenti misuratori della
temperatura dell’aria tra -20 °C e 60 °C. L’INRIM possiede le CMC in questo settore tra -20 °C e 80 °C, l’IMBIH
utilizzerebbe gli eventuali risultati positivi per dimostrare le proprie capacità metrologiche come evidenza
per la richiesta delle CMC nel settore in oggetto. Entrambi i laboratori hanno tarato un set di tre termometri
e solo il migliore sotto il profilo della stabilità nel tempo è stato scelto come campione di trasferimento.
Inizialmente il TC-T Chair Dott. S. Rudtsch ha partecipato all’esercizio come terza parte indipendente, poi è
stato sostituito dal suo successore Dott. M. Sadli.
L’attività era stata inizialmente pianificata come attività collaterale al progetto EURAMET P1456 ATM (Air
Temperature Metrology) ma poi è stata ri-pianificata come attività indipendente nel progetto EURAMET
P1586.To demonstrate the technical competence of IMBIH with respect to the calibration of air temperature
sensors/transducers/meters between -20 °C and 60 °C, in order to get support evidences to claim CMCs in
this sector, a hybrid measurement comparison was performed with INRiM which already has published CMCs
for this kind of instruments in the range between -20 °C to 80 °C. The comparison involved three UUTs as
transfer instrument but only the best one was chosen as the comparison transfer standard.
Firstly, the EURAMET TC-T Chair Doc. S. Rudtsch was informed in advance about the comparison and agreed
to act as the third independent party then he was substituted by his successor Doc. M. Sadli.
The activity was initially planned as part of the EURAMET project P1456 ATM (Air Temperature Metrology)
but successively it was planned as an independent exercise in the EURAMET project P158
COAT Project: Intercomparison of Thermometer Radiation Shields in the Arctic
No full textA metrological field intercomparison of thermometer radiation shields in the Arctic was conducted with the aim of obtaining information to increase the worldwide comparability of air temperature measurements. Air temperature measurements are performed by different combinations of thermometers and shields. The response of each system (thermometer + shield) to local meteorological conditions depends on the system itself, limiting the comparability of air temperature measurements. Ten different models of radiation shields were included in the intercomparison, involving two campaigns: (1) the laboratory campaign, where all the instrumentation was calibrated just before and just after the field campaign, and (2) the field campaign that lasted 14 months where 41 thermometers were sampled every 2 min. All the delivered data were subjected to quality control to assure the robustness of the conclusions. A reference shield was defined, and the other shields were compared to the reference one for the conditions where maximum divergences were expected, solar irradiance being the highest impact factor. A maximum divergence value of 1.29 °C was derived for one of the shields and, for all the shields, the difference from the reference one decreases with wind speed. Finally, the uncertainties associated with the shields intercomparison were calculated
