Search results for "physics.atom-ph"
showing 10 items of 395 documents
Formation of narrow optical resonances in thin atomic vapor layers of Cs, Rb, K and applications.
2019
This thesis presents the study of coherent light interaction with a sub-wavelength atomic alkali vapor layer confined in a nano-cell and applications for the formation of narrow optical resonances.We develop a theoretical model describing the resonant interaction of the laser light with the thin alkali vapor layer in the presence of an external static magnetic field. We show that due to a transient regime of interaction, only slow atoms contribute to the signal and their transmission spectrum is essentially Doppler-free. The nature of the obtained spectra makes the transmission spectroscopy from a nano-cell a convenient technique to perform studies of closely-spaced atomic transitions and i…
Selective reflection spectroscopy of alkali vapors confined in nanocells and emerging sensing applications
2019
This thesis is aimed at studying the resonant interaction of a laser radiation with an atomic alkali vapor layer of wavelength-scale thickness confined in an optical nanocell; and emerging sensing applications.We focus our attention on the selective reflection arising at the interface between a dielectric window and a resonant alkali vapor, and show that the derivative of selective reflection spectra exhibit narrow resonances whose maxima are located exactly at atomic resonance frequencies. These resonances are observed with a spectral linewidth up to fifteen times smaller than the Doppler linewidth of the medium and their amplitudes scale linearly with respect to the transitions ones. Owin…
Echo-assisted impulsive alignment of room-temperature acetone molecules
2021
International audience; We experimentally and theoretically investigate the field-free alignment of the asymmetric-top acetone molecule. Our study shows that the production of postpulse aligned molecules in a dense sample (0.05-0.2 bar) of room-temperature acetone using a single-pulse excitation can be significantly improved by rotational alignment echoes induced in a two-pulse excitation scheme. We report the observation of fractional echoes that can be used to reveal the nonlinearity of the molecular system. In a proof-of-principle experiment, a pre-aligned sample of acetone is also used for third-harmonic generation. The analysis of the experimental data with numerical simulations based …
The proton radius puzzle
2017
High-precision measurements of the proton radius from laser spectroscopy of muonic hydrogen demonstrated up to six standard deviations smaller values than obtained from electron-proton scattering and hydrogen spectroscopy. The status of this discrepancy, which is known as the proton radius puzzle will be discussed in this paper, complemented with the new insights obtained from spectroscopy of muonic deuterium.
New theoretical and experimental concepts for frequency generation in optical fibers: modulation instability, pulsed Raman Laser and kinetic approach…
2009
Following a brief introduction to optical fibers, we combine the effect of modulational instability and Raman self-frequency shift to generate a frequency combs with a spectral width higher than 100 nm and a central frequency shifted towards higher wavelengths. Then, the stimulated Raman effect is used in a ring cavity coupled with nonlinear polarization rotation and polarization filtering. A pulsed regime is obtained at the wavelength of the first Stokes emission and presents a rich zoology of experimental dynamic pulsed regimes. A second main line of this manuscript considers the incoherent regime of supercontinuum generation. We show that under certain conditions, the spectral broadening…
Production of photon states from Λ-atoms in a cavity
2019
We analyse the system of Λ-atoms in a cavity QED of semi-transparent mirror and driven by laser fields. We derive effective models and connect concepts (photonic flux, input-output operators, photonic state) characterizing the propagation of the resulting leaking photons. We propose an atom-cavity non-resonant scheme for single-and 2-photons generation. The pulse shapes of outgoing single photons are tailored using a specifically designed driving field envelope. For the production of 2-photon states, two trapped atoms are used with two driving pulses. Their pulse shapes are characterized and it is shown that the multiphoton outgoing photonic states cannot be Fock states, since the photons a…
Residual Phase Noise Measurement of Optical Second Harmonic Generation in PPLN Waveguides
2017
We report on the characterization, including residual phase noise and fractional frequency instability, of fiber-coupled PPLN non-linear crystals. These components are devoted to frequency doubling 871 nm light from an extended-cavity diode laser to produce a 435.5 nm beam, corresponding to the ytterbium ion electric quadrupole clock transition. We measure doubling efficiencies of up to 117.5 %/W. Using a Mach-Zehnder interferometer and an original noise rejection technique, the residual phase noise of the doublers is estimated to be lower than ${\rm -35\, dBrad^2/Hz}$ at 1 Hz, making these modules compatible with up-to-date optical clocks and ultra-stable cavities. The influence of externa…
Phase-Noise and Amplitude-Noise Measurement of DACs and DDSs
2019
This article proposes a method for the measurement of Phase Noise (PN, or PM noise) and Amplitude Noise (AN, or AM noise) of Digital-to-Analog Converters (DAC) and Direct Digital Synthesizers (DDS) based on modulation-index amplification. The carrier is first reduced by a controlled amount (30-40 dB) by adding a reference signal of nearly equal amplitude and opposite in phase. Then, residual carrier and noise sidebands are amplified and sent to a conventional PN analyzer. The main virtues of our method are: (i) the noise specs of the PN analyzer are relaxed by a factor equal to the carrier suppression ratio; and, (ii) the capability to measure the AN using a PN analyzer, with no need for th…
Search for Axionlike Dark Matter through Nuclear Spin Precession in Electric and Magnetic Fields
2017
We report on a search for ultralow-mass axionlike dark matter by analyzing the ratio of the spinprecession frequencies of stored ultracold neutrons and 199Hg atoms for an axion-induced oscillating electric dipole moment of the neutron and an axion-wind spin-precession effect. No signal consistent with dark matter is observed for the axion mass range 10−24 ≤ ma ≤ 10−17 eV. Our null result sets the first laboratory constraints on the coupling of axion dark matter to gluons, which improve on astrophysical limits by up to 3 orders of magnitude, and also improves on previous laboratory constraints on the axion coupling to nucleons by up to a factor of 40. ispartof: Physical Review X vol:7 issue:…
ALIGNEMENT UNI ET TRIDIMENSIONNEL DE MOLÉCULES PAR IMPULSION LASER FEMTOSECONDE
2007
This thesis is devoted to the study of the alignment of linear and asymmetric top molecules generated by an intense laser pulse. In the case of short pulses with respect to molecular rotation, periodic alignment appears in field-free conditions after the extinction of the field. We study theoretically and experimentally the effects of intensity, temperature and polarization of the electric field on produced alignment. If the field is linearly polarized, the interaction leads to the alignment of the most polarizable axis of the molecule. If the field is elliptically polarized, the pulse can generate a simultaneous alignment of the three principal axes of inertia of an asymmetric top molecule…