615 research outputs found
Conversion of bright magneto-optical resonances into dark at fixed laser frequency for D2 excitation of atomic rubidium
Nonlinear magneto-optical resonances on the hyperfine transitions belonging
to the D2 line of rubidium were changed from bright to dark resonances by
changing the laser power density of the single exciting laser field or by
changing the vapor temperature in the cell. In one set of experiments atoms
were excited by linearly polarized light from an extended cavity diode laser
with polarization vector perpendicular to the light's propagation direction and
magnetic field, and laser induced fluorescence (LIF) was observed along the
direction of the magnetic field, which was scanned. A low-contrast bright
resonance was observed at low laser power densities when the laser was tuned to
the Fg=2 --> Fe=3 transition of Rb-87 and near to the Fg=3 --> Fe=4 transition
of Rb-85. The bright resonance became dark as the laser power density was
increased above 0.6mW/cm2 or 0.8 mW/cm2, respectively. When the Fg=2 --> Fe=3
transition of Rb-87 was excited with circularly polarized light in a second set
of experiments, a bright resonance was observed, which became dark when the
temperature was increased to around 50C. The experimental observations at room
temperature could be reproduced with good agreement by calculations based on a
theoretical model, although the theoretical model was not able to describe
measurements at elevated temperatures, where reabsorption was thought to play a
decisive role. The model was derived from the optical Bloch equations and
included all nearby hyperfine components, averaging over the Doppler profile,
mixing of magnetic sublevels in the external magnetic field, and a treatment of
the coherence properties of the exciting radiation field.Comment: 9 pages, 7 figure
Optical response of a misaligned and suspended Fabry-Perot cavity
The response to a probe laser beam of a suspended, misaligned and detuned
optical cavity is examined. A five degree of freedom model of the fluctuations
of the longitudinal and transverse mirror coordinates is presented. Classical
and quantum mechanical effects of radiation pressure are studied with the help
of the optical stiffness coefficients and the signals provided by an FM
sideband technique and a quadrant detector, for generic values of the product
of the fluctuation frequency times the cavity round trip. A
simplified version is presented for the case of small misalignments. Mechanical
stability, mirror position entanglement and ponderomotive squeezing are
accommodated in this model. Numerical plots refer to cavities under test at the
so-called Pisa LF facility.Comment: 14 pages (4 figures) submitted to Phys. Rev.
Draw me a Neutrino: the first KM3NeT art contest
[EN] While the KM3NeT neutrino detector is being deployed in the Mediterranean Sea, the Collaboration
launched a contest searching for illustrations of the neutrinos it will detect. The participants
in the contest were invited to submit their interpretation of a neutrino, using any technique. More
than 500 drawings were submitted from sixteen different countries. The winners were selected
by a jury of scientists, artists and science communicators based on the originality and creativity
of the drawings, as well as the harmony with the properties and origin of the neutrinos. After
announcing the results in an online ceremony with a large international audience, the winning
drawings have been put on display in a dedicated KM3NeT Virtual Neutrino Art Centre. In this
contribution, we will explain the motivation for the contest and will describe how it was organized.
We will also show the winning drawings and present the results of an impact study carried out
during the contest.We thank Angelo Ceres of Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Bari, for
setting up the contest website. The contest was supported in France from Centre National de la
Recherche Scientifique (CNRS) and LabEx UnivEarthS (ANR-10-LABX-0023 and ANR-18-IDEX0001). G. de Wasseige acknowledges support from the European UnionÂżs Horizon 2020 research
and innovation programme under the Marie Sklodowska-Curie grant agreement No 844138.Circella, M.; Ardid RamĂrez, M.; Bendahman, M.; Bozza, C.; Coyle, P.; Wasseige, G.; Distefano, C.... (2022). Draw me a Neutrino: the first KM3NeT art contest. PoS. Proceedings of Science. 1-10. https://doi.org/10.22323/1.395.140011
Continuous variable entanglement by radiation pressure
We show that the radiation pressure of an intense optical field impinging on
a perfectly reflecting vibrating mirror is able to entangle in a robust way the
first two optical sideband modes. Under appropriate conditions, the generated
entangled state is of EPR type [A. Einstein, {\it et al.}, Phys. Rev. {\bf 47},
777 (1935)].Comment: 11 pages, 3 figure
Entangling macroscopic oscillators exploiting radiation pressure
It is shown that radiation pressure can be profitably used to entangle {\it
macroscopic} oscillators like movable mirrors, using present technology. We
prove a new sufficient criterion for entanglement and show that the achievable
entanglement is robust against thermal noise. Its signature can be revealed
using common optomechanical readout apparatus.Comment: 4 pages, 2 eps figures, new separability criterion added, new figure
2, authors list change
Mirror quiescence and high-sensitivity position measurements with feedback
We present a detailed study of how phase-sensitive feedback schemes can be
used to improve the performance of optomechanical devices. Considering the case
of a cavity mode coupled to an oscillating mirror by the radiation pressure, we
show how feedback can be used to reduce the position noise spectrum of the
mirror, cool it to its quantum ground state, or achieve position squeezing.
Then, we show that even though feedback is not able to improve the sensitivity
of stationary position spectral measurements, it is possible to design a
nonstationary strategy able to increase this sensitivity.Comment: 25 pages, 11 figure
Continuous variable entanglement and quantum state teleportation between optical and macroscopic vibrational modes through radiation pressure
We study an isolated, perfectly reflecting, mirror illuminated by an intense
laser pulse. We show that the resulting radiation pressure efficiently
entangles a mirror vibrational mode with the two reflected optical sideband
modes of the incident carrier beam. The entanglement of the resulting
three-mode state is studied in detail and it is shown to be robust against the
mirror mode temperature. We then show how this continuous variable entanglement
can be profitably used to teleport an unknown quantum state of an optical mode
onto the vibrational mode of the mirror.Comment: 18 pages, 10 figure
Spin randomization of light-induced desorbed Rb atoms
We present the first experimental observation of atomic spin randomization of Rb atoms released by light-induced atomic desorption (LIAD). A natural mixture of Rb atoms contained in paraffin and PDMS coated glass cells is irradiated by a free-running diode laser light tuned to the Rb D2 resonance line. The transmission spectrum of the Rb vapor is thus modified and shows a strong enhancement of the hyperfine optical pumping as the light intensity is increased and the laser-frequency scanning rate is decreased. The D2 line spectra are compared for two cases: without and with illumination of the walls of the cell by a UV lamp centered around the wavelength of 404 nm. A simple theoretical model based on the solution of the rate balance equations is introduced in order to analyze the experimental results
Treatment-Free Remission in Chronic Myeloid Leukemia Patients Treated With Low-Dose TKIs: A Feasible Option Also in the Real-Life. A Campus CML Study
Treatment-free remission (TFR) has become a primary therapeutic goal in CML and is also considered feasible by international guidelines. TKIs dose reduction is often used in real-life practice to reduce adverse events, although its impact on TFR is still a matter of debate. This study aimed to explore the attitude of Italian hematologists towards prescribing TKIs at reduced doses and its impact on TFR. In September 2020, a questionnaire was sent to 54 hematology centers in Italy participating to the Campus CML network. For each patient, data on the main disease characteristics were collected. Most of the hematologists involved (64.4%) believed that low-dose TKIs should not influence TFR. Indeed, this approach was offered to 194 patients. At the time of TFR, all but 3 patients had already achieved a DMR, with a median duration of 61.0 months. After a median follow-up of 29.2 months, 138 (71.1%) patients were still in TFR. Interestingly, TFR outcome was not impaired by any of the variables examined, including sex, risk scores, BCR-ABL1 transcript types, previous interferon, type and number of TKIs used before treatment cessation, degree of DMR or median duration of TKIs therapy. On the contrary, TFR was significantly better after dose reduction due to AEs; furthermore, patients with a longer DMR duration showed a trend towards prolonged TFR. This survey indicates that low-dose TKI treatment is an important reality. While one third of Italian hematologists still had some uncertainties on TFR feasibility after using reduced doses of TKIs outside of clinical trials, TFR has often been considered a safe option even in patients treated with low-dose TKIs in the real-life setting. It should be noted that only 28.9% of our cases had a molecular recurrence, less than reported during standard dose treatment. Consequently, TFR is not impaired using low-dose TKIs
Classification of Light-Induced Desorption of Alkali Atoms in Glass Cells Used in Atomic Physics Experiments
We attempt to provide physical interpretations of light-induced desorption
phenomena that have recently been observed for alkali atoms on glass surfaces
of alkali vapor cells used in atomic physics experiments. We find that the
observed desorption phenomena are closely related to recent studies in surface
science, and can probably be understood in the context of these results. If
classified in terms of the photon-energy dependence, the coverage and the
bonding state of the alkali adsorbates, the phenomena fall into two categories:
It appears very likely that the neutralization of isolated ionic adsorbates by
photo-excited electron transfer from the substrate is the origin of the
desorption induced by ultraviolet light in ultrahigh vacuum cells. The
desorption observed in low temperature cells, on the other hand, which is
resonantly dependent on photon energy in the visible light range, is quite
similar to light-induced desorption stimulated by localized electronic
excitation on metallic aggregates. More detailed studies of light-induced
desorption events from surfaces well characterized with respect to alkali
coverage-dependent ionicity and aggregate morphology appear highly desirable
for the development of more efficient alkali atom sources suitable to improve a
variety of atomic physics experiments.Comment: 6 pages, 1 figure; minor corrections made, published in e-Journal of
Surface Science and Nanotechnology at
http://www.jstage.jst.go.jp/article/ejssnt/4/0/4_63/_articl
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