| 20 gennaio
Partecipazione INRIM al confronto 'Supplementary Comparison EURAMET.EM-S32'
"Comparison of resistance standards at 1 TΩ and 100 TΩ":
sistemi di misura INRIM, analisi dei dati e interazioni con il Laboratorio pilota
Nel 2009 l'INRIM ha partecipato al confronto di misura EURAMET.EM-S32 di elevatissime
resistenze a livello 1 TΩ e 100 TΩ a cui hanno partecipato 18 Istituti Metrologici Europei.
Vengono descritti i sistemi ed incertezze di misura INRIM, l'analisi dei risultati
per il trattamento di dati provenienti da più campioni di pari valor nominale.
Viene sintetizzata l'interazione tra l'INRIM ed il METAS per la definizione dell'esito definitivo del confronto.
Flavio Galliana e Pier Paolo Capra
| 22 gennaio
Cold atoms experiments at University of São Paulo:
from quantum turbulence to compact atomic clocks
We shall discuss the experiments and results using cold atoms to
prepare BEC, to investigate quantum turbulence and to produce atomic
clocks. In special, the compact clock, using an expanding cloud of
cold atoms will be discussed.
Vanderlei Salvador Bagnato
Instituto de Física de São Carlos
Universidade de São Paulo
| 3 febbraio
Photonic States Manipulation in Atomic Ensembles
Quantum information processing requires efficient encoding, manipulation
and storage of quantum states.
Photons are excellent carriers of quantum information, since they travel
fast without being affected by external disturbances. On the other hand,
cold atomic ensembles are a very versatile tool to store, manipulate and
retrieve quantum states of light. In the past decade, they have been
extensively used to store and retrieve photonic states by using either
the so called Electromagnetically Induced Transparency (EIT) protocol,
or the DLCZ protocol, where the detection of a Raman photon triggers the
creation of a collective atomic excitation in a lambda-medium. The shared
excitation can be reconverted later into a single photon leaving the ensemble.
The process has been extensively investigated in the photon counting regime
showing the non-classical character of the emerging photonic state.
Only very recently the photonic states leaving the atomic ensemble have been
characterized by quantum homodyne tomography. The state is hence completely
described in the continuous variables picture by the reconstructed Wigner
function giving complete information on a welldefined spatial-temporal mode.
Atomic ensembles can be also used for manipulating photonic states by atomic
interactions and they are promising candidates to reach strong-nonlinearities
at the single-photon level. Photonic states can be converted into strongly
interacting particles, like collective excitations involving Rydberg atoms.
Interactions between Rydbergs in fact lead to a "blockade" phenomenon, where
each Rydberg atom blocks the excitation of its neighbors, which can result
in strong nonlinearities.
Laboratoire Kastler Brossel
Université Pierre et Marie Curie, Ecole Normale Supérieure, CNRS, Paris
| 12 febbraio
Including disorder in micromagnetic simulations: the road to imperfection
In this seminar you will see how material imperfections can be included in
micromagnetic simulations. Understanding domain wall motion in magnetic
nanowires is of paramount importance for the development of future spintronics
devices and simulations are a powerful tool to investigate this motion. However,
more often than not the effects of material imperfections are not taken into
account in these simulations.
A method will be shown to characterize simulated defects and its application
to find 2 possible implementations that give rise to defects with properties
that correspond to experimental values. The effects of this disorder on current
driven vortex domain wall motion will illustrate why disorder should be taken
into account. Furthermore, as there is a suspected link between the experimentally
measured disorder and the grains in material samples. A computationally efficient
way of simulating polycrystalline materials using voronoi cells will also be presented.
University of Ghent
| 12 febbraio
Astroparticle physics in space
Università di Trento
Dipartimento di Fisica
| 19 febbraio
Optical Lattice Clocks and Applications
Research on optical frequency standards based on cold atoms or ions has shown a great
advance in the last few years.
Among others, alkaline-earth atoms trapped in an optical lattice have demonstrated
Recently a strontium lattice clock demonstrated an uncertainty of 6e-18, the best in
frequency standards up to date.
The stability and accuracy of optical frequency standards will benefit many applications
and innovations, such as realization and dissemination of units in the Système International
(SI), quantum simulations, relativistic geodesy, test of fundamental constants variation and
tests of fundamental physics.
In the talk I will describe the development of an optical lattice clock based on ytterbium
atoms and the perspective for the near future.
Comparison with other clocks is planned, both local and remote, that will allow a
proof-of-principle relativistic geodesy experiment.
In addition, remote comparison with a quantum degenerate ytterbium gas experiment developed
in Florence will be useful for studies of collisional physics and quantum simulations.
| 26 febbraio
Un'infrastruttura in fibra ottica per la disseminazione di frequenza a 5e-19 su scala nazionale ed europea
A fiber optical link for frequency dissemination at 5e-19 on a European scale
Currently, time and frequency dissemination is performed with satellite microwave links. These techniques strongly limit
the comparison of remote primary frequency standards, and are completely inadequate for the comparison of optical clocks.
In recent years, an alternative method based on optical fiber has been developed, which improves the resolution by 5 orders
of magnitude. This is not only beneficial in time and frequency metrology, but paves the way for new opportunities in
fundamental physics, geodesy and radioastronomy as well.
INRIM has developed a 642 km optical link with the European Laboratory for Non Linear Spectroscopy (LENS) in Firenze.
This backbone has enabled absolute spectroscopic measurements between the two laboratories and will be upgraded to connect
other research centres in Italy ( Medicina (Bologna) Radio-telescopes, National Institute of Optics in Firenze,
National Council of Research in Milano) and in Europe. I will describe the optical link, the fiber-based remote comparison
of atomic clocks, and the future applications.
| 27 marzo
Comparison of non-classicality and Decoherence between photon added and photon subtracted squeezed coherent state
Non-classicality in a state of light is a valuable resource for quantum information processing.
Non-classicality is manifested by certain criteria such as sub-Poissonian distribution of photon numbers,
oscillation in the photon number distribution and negativity of the Wigner function.
Employing the technique of Integration within an Ordered Product (IWOP), I have calculated and compared
the non-classicality of photon added and photon subtracted squeezed coherent states. I have found that
photon addition generates more non-classicality in a squeezed coherent state than photon subtraction.
Decoherence of such states in amplitude and phase damping channel has also been analysed in this work.
How the photon number distribution will change under the influence of Decoherence will also be discussed.
| 11 aprile
Dai vulcani siciliani ai villaggi neolitici piemontesi.
Il viaggio dell'ossidiana attraverso lo studio delle sue proprietà magnetiche
In questo lavoro, si à posta attenzione ad alcuni parametri sperimentali per distinguere le diverse
distribuzioni e dimensioni dei granuli magnetici (ossidi di ferro: magnetite, titano-magnetite) nei principali
giacimenti di ossidiana del Mediterraneo. La potenzialità del metodo per tracciare la provenienza di
manufatti in ossidiana di interesse archeologico è stata valutata confrontando campioni geologici di
cinque isole (Lipari, Monte Arci – Sardegna, Palmarola, Pantelleria, Melos) con i campioni costitutivi di
una collezione di lamelle provenienti dal sito neolitico di Castello d'Annone, in provincia di Asti (22 campioni).
Sono state misurate: la suscettività magnetica iniziale x, la suscettività anisteretica xa e
la magnetizzazione rimanente (IRM) a T = 293 K (IRM293) e 77 K (IRM77). Sono state inoltre analizzate
le forme dei cicli di isteresi, sia a T = 293 K sia a T = 77 K. Lo studio dei parametri magnetici ricavabili
da queste misure permette una stima della distribuzione dei granuli ferrosi presenti nell'ossidiana,
distinguendone il contenuto in superparamagnetici (SP), singolo dominio (SD), pseudo singolo dominio (PSD)
e multidominio (MD). L'indicazione di provenienza ricavata dalle misure conferma le ipotesi già avanzate
dagli studi archeologici nell'Italia nord-occidentale sull'esistenza nel Neolitico di una via di commercio con
Lipari e la Sicilia, oltre a quella con la Sardegna, consolidata e favorita dalla vicinanza.
Università di Torino
| 14 aprile
Control of Quantum Sensors
The success of quantum-enhanced sensors relies on precise control of the experimental systems to
protect them from undesired sources of noise. Unfortunately, simple application of known strategies
to reduce decoherence does not necessarily translate into an improvement of phase measurements:
techniques such as dynamical decoupling that eliminate decoherence also eliminate the very signal
that one wishes to measure.
In this talk I will show how to extend control techniques to quantum metrology tasks, achieving a
better and more flexible compromise between sensitivity and noise protection. In addition,
tailoring the sensor dynamic can help reveal temporal and spatial information about the target.
We can for example use coherent control of quantum sensors to simultaneously reconstruct the
arbitrary profile of timevarying fields and correct for unwanted noise sources; or we can
achieve high frequency resolution, thus allowing precise spectroscopy.
I will illustrate applications of these strategies in experimental implementations based
on the NitrogenVacancy center in diamond.
Nuclear Science and Engineering Department
Massachusetts Institute of Technology
| 15 aprile
Atomic Frequency Standards in Brazil - Research and ongoing applications
In the recent years, using atomic transitions have become more and more frequent
in the definition of reference standards. The measurement capability reached by microwave
and optical frequency standards plays a fundamental role on these definitions.
Our research group has been establishing experiments in some of the several kinds of
atomic standards, and the goal of this presentation is to present the state of the art
in our laboratories. The results concern the 133Cs atomic fountain, the 133Cs compact
clock, the experiment with 88Sr, the structure under development for time and frequency
scientific metrology and applications in course for the use of such accurate and stable references.
Daniel Varela Magalhaes
São Carlos School of Engineering
University of São Paulo, Brazil