arXiv subjects

Pierre Lemonde

Publications and source records attributed to Pierre Lemonde.

At least 19 recordsLinked to original sources

arXiv2026

Refractive indices of Y$_2$SiO$_5$ in the near-infrared

Y$_2$SiO$_5$ is a reference birefringent material for optical quantum technologies. The refractive index is primarily known in the visible spectrum, whereas this crystal is also used in the near-infrared. We begin by analysing historical measurements, as well as the modelling proposed at the time. The absence of refractive index tabulated values in the near- and mid-infrared ranges motivated us to carry out independent measurements. Using interferometric techniques in the telecom wavelength range, we demonstrate the ability to determine the principal refractive indices and propose a model spanning a broad spectral range based on Sellmeier equations for which we explicitly give the coefficients and discuss the achievable accuracy. Conversely, as an illustration, white-light interference enables us to precisely determine the thickness of a Y$_2$SiO$_5$ thin film on the order of ten micrometers.

physics.optics↗

arXiv2024

Opto-RF transduction in Er$^{3+}$:CaWO$_4$

We use an erbium doped CaWO$_4$ crystal as a resonant transducer between the RF and optical domains at 12 GHz and 1532 nm respectively. We employ a RF resonator to enhance the spin coupling but keep a single-pass (non-resonant) optical setup. The overall efficiency is low but we carefully characterize the transduction process and show that the performance can be described by two different metrics that we define and distinguish: the electro-optics and the quantum efficiencies. We reach an electro-optics efficiency of -84 dB for 15.7 dBm RF power. The corresponding quantum efficiency is -142 dB for 0.4 dBm optical power. We develop the Schr\"odinger-Maxwell formalism, well-known to describe light-matter interactions in atomic systems, in order to model the conversion process. We explicitly make the connection with the cavity quantum electrodynamics (cavity QED) approach that are generally used to describe quantum transduction.

quant-ph↗

arXiv2011

Observation and cancellation of the dc Stark shift in strontium optical lattice clocks

We report on the observation of a dc Stark frequency shift at the $10^{-13}$ level by comparing two strontium optical lattice clocks. This frequency shift arises from the presence of electric charges trapped on dielectric surfaces placed under vacuum close to the atomic sample. We show that these charges can be eliminated by shining UV light on the dielectric surfaces, and characterize the residual dc Stark frequency shift on the clock transition at the $10^{-18}$ level by applying an external electric field. This study shows that the dc Stark shift can play an important role in the accuracy budget of lattice clocks, and should be duly taken into account.

physics.atom-ph↗

arXiv2011

Application of lasers to ultracold atoms and molecules

In this review, we discuss the impact of the development of lasers on ultracold atoms and molecules and their applications. After a brief historical review of laser cooling and Bose-Einstein condensation, we present important applications of ultra cold atoms, including time and frequency metrology, atom interferometry and inertial sensors, atom lasers, simulation of condensed matter systems, production and study of strongly correlated systems, and production of ultracold molecules.

cond-mat.quant-gas↗

arXiv2011

Lattice Induced Frequency Shifts in Sr Optical Lattice Clocks at the $10^{-17}$ Level

We present a comprehensive study of the frequency shifts associated with the lattice potential for a Sr lattice clock. By comparing two such clocks with a frequency stability reaching $5\times 10^{-17}$ after a one hour integration time, and varying the lattice depth up to $U_0=900 \, E_r$ with $E_r$ being the recoil energy, we evaluate lattice related shifts with an unprecedented accuracy. We put the first experimental upper bound on the recently predicted frequency shift due to the magnetic dipole (M1) and electric quadrupole (E2) interactions. This upper bound is significantly smaller than the theoretical upper limit. We also give a new upper limit on the effect of hyperpolarizability with an improvement by more than one order of magnitude. Finally, we report the first observation of the vector and tensor shifts in a lattice clock. Combining these measurements, we show that all known lattice related perturbation will not affect the clock accuracy down to the $10^{-17}$ level, even for very deep lattices, up to $U_0=150\,E_r$.

physics.atom-ph↗

arXiv2010

A coherent optical link through the turbulent atmosphere

We describe the realization of a 5 km free space coherent optical link through the turbulent atmosphere between a telescope and a ground target. We present the phase noise of the link, limited mainly by atmospheric turbulence and mechanical vibrations of the telescope and the target. We discuss the implications of our results for applications, with particular emphasis on optical Doppler ranging to satellites and long distance frequency transfer.

physics.optics↗

arXiv2010

An agile laser with ultra-low frequency noise and high sweep linearity

We report on a fiber-stabilized agile laser with ultra-low frequency noise. The frequency noise power spectral density is comparable to that of an ultra-stable cavity stabilized laser at Fourier frequencies higher than 30 Hz. When it is chirped at a constant rate of ~ 40 MHz/s, the max non-linearity frequency error is about 50 Hz peak-to-peak over more than 600 MHz tuning range. The Rayleigh backscattering is found to be a significant frequency noise source dependent on fiber length, chirping rate and the power imbalance of the interferometer arms. We analyze this effect both theoretically and experimentally and put forward techniques to reduce this noise contribution.

physics.optics↗

arXiv2009

Minimizing the Dick Effect in an Optical Lattice Clock

We discuss the minimization of the Dick effect in an optical lattice clock. We show that optimizing the time sequence of operation of the clock can lead to a significant reduction of the clock stability degradation by the frequency noise of the interrogation laser. By using a non-destructive detection of the atoms, we are able to recycle most of the atoms between cycles and consequently to strongly reduce the time spent capturing the atoms in each cycle. With optimized parameters, we expect a fractional Allan deviation better than 2E-16$τ^{-1/2}$ for the lattice clock.

physics.atom-ph↗

arXiv2009

Non-destructive measurement of the transition probability in a Sr optical lattice clock

We present the experimental demonstration of non-destructive probing of the 1S0-3P0 clock transition probability in an optical lattice clock with 87Sr atoms. It is based on the phase shift induced by the atoms on a weak off-resonant laser beam. The method we propose is a differential measurement of this phase shift on two modulation sidebands with opposite detuning with respect to the 1S0-1P1 transition, allowing a detection limited by the photon shot noise. We have measured an atomic population of 10^4 atoms with a signal to noise ratio of 100 per cycle, while keeping more than 95% of the atoms in the optical lattice with a depth of 0.1 mK. The method proves simple and robust enough to be operated as part of the whole clock setup. This detection scheme enables us to reuse atoms for subsequent clock state interrogations, dramatically reducing the loading time and thereby improving the clock frequency stability.

quant-ph↗

arXiv2009

Ultra low frequency noise laser by locking to an optical fiber delay line

We report the frequency stabilization of an erbium-doped fiber distributed-feedback laser using an all-fiber based Michelson interferometer of large arm imbalance. The interferometer uses a 1 km SMF-28 optical fiber spool and an acousto optic modulator allowing heterodyne detection. The frequency noise power spectral density is reduced by more than 40 dB for Fourier frequencies ranging from 1 Hz to 10 kHz, corresponding to a level well below 1 Hz^2/Hz over the whole range. It reaches 10^{-2} Hz^2/Hz at 1 kHz. Between 40 Hz and 30 kHz, the frequency noise is shown to be comparable to the one obtained by Pound-Drever-Hall locking to a high finesse Fabry-Perot cavity. Locking to a fiber delay line could consequently represent a reliable, simple and compact alternative to cavity stabilization for short term linewidth reduction.

physics.ins-det↗

arXiv2008

Long-distance frequency transfer over an urban fiber link using optical phase stabilization

We transferred the frequency of an ultra-stable laser over 86 km of urban fiber. The link is composed of two cascaded 43-km fibers connecting two laboratories, LNE-SYRTE and LPL in Paris area. In an effort to realistically demonstrate a link of 172 km without using spooled fiber extensions, we implemented a recirculation loop to double the length of the urban fiber link. The link is fed with a 1542-nm cavity stabilized fiber laser having a sub-Hz linewidth. The fiber-induced phase noise is measured and cancelled with an all fiber-based interferometer using commercial off the shelf pigtailed telecommunication components. The compensated link shows an Allan deviation of a few 10-16 at one second and a few 10-19 at 10,000 seconds.

physics.ins-det↗

arXiv2007

An Optical Lattice Clock with Spin-polarized 87Sr Atoms

We present a new evaluation of an 87Sr optical lattice clock using spin polarized atoms. The frequency of the 1S0-3P0 clock transition is found to be 429 228 004 229 873.6 Hz with a fractional accuracy of 2.6 10^{-15}, a value that is comparable to the frequency difference between the various primary standards throughout the world. This measurement is in excellent agreement with a previous one of similar accuracy.

physics.atom-ph↗

arXiv2007

Accuracy Evaluation of an Optical Lattice Clock with Bosonic Atoms

We report the first accuracy evaluation of an optical lattice clock based on the 1S0 - 3P0 transition of an alkaline earth boson, namely 88Sr atoms. This transition has been enabled using a static coupling magnetic field. The clock frequency is determined to be 429 228 066 418 009(32) Hz. The isotopic shift between 87Sr and 88Sr is 62 188 135 Hz with fractional uncertainty 5.10^{-7}. We discuss the conditions necessary to reach a clock accuracy of 10^{-17} or less using this scheme.

physics.atom-ph↗

arXiv2006

From Optical Lattice Clocks to the Measurement of Forces in the Casimir Regime

We describe a novel experiment based on atoms trapped close to a macroscopic surface, to study the interactions between the atoms and the surface at very small separations (0.6 to 10 $μ$m). In this range the dominant potential is the QED interaction (Casimir-Polder and Van der Waals) between the surface and the atom. Additionally, several theoretical models suggest the possibility of Yukawa type potentials with sub-mm range, arising from new physics related to gravity. The proposes set-up is very similar to neutral atom optical lattice clocks, but with the atoms trapped in lattice sites close to the reflecting mirror. A sequence of pulses of the probe laser at different frequencies is then used to create an interferometer with a coherent superposition between atomic states at different distances from the mirror (in different lattice sites). Assuming atom interferometry state of the art measurement of the phase difference and a duration of the superposition of about 0.1 s we expect to be able to measure the potential difference between separated states with an uncertainty of $\approx 10^{-4}$ Hz. An analysis of systematic effects for different atoms and surfaces indicates no fundamentally limiting effect at the same level of uncertainty, but does influence the choice of atom and surface material. Based on those estimates, we expect that such an experiment would improve the best existing measurements of the atom-wall QED interaction by $\geq$ 2 orders of magnitude, whilst gaining up to 4 orders of magnitude on the best present limits on new interactions in the range between 100 nm and 100 $μ$m.

physics.atom-ph↗

arXiv2006

An accurate optical lattice clock with 87Sr atoms

We report a frequency measurement of the 1S0-3P0 transition of 87Sr atoms in an optical lattice clock. The frequency is determined to be 429 228 004 229 879 (5) Hz with a fractional uncertainty that is comparable to state-of-the-art optical clocks with neutral atoms in free fall. Two previous measurements of this transition were found to disagree by about 2x10^{-13}, i.e. almost four times the combined error bar, instilling doubt on the potential of optical lattice clocks to perform at a high accuracy level. In perfect agreement with one of these two values, our measurement essentially dissipates this doubt.

physics.atom-ph↗

arXiv2005

Hyperpolarizability effects in a Sr optical lattice clock

We report the observation of the higher order frequency shift due to the trapping field in a $^{87}$Sr optical lattice clock. We show that at the magic wavelength of the lattice, where the first order term cancels, the higher order shift will not constitute a limitation to the fractional accuracy of the clock at a level of $10^{-18}$. This result is achieved by operating the clock at very high trapping intensity up to $400 $kW/cm$^2$ and by a specific study of the effect of the two two-photon transitions near the magic wavelength.

physics.atom-ph↗

arXiv2005

An optical clock with neutral atoms confined in a shallow trap

We study the trap depth requirement for the realization of an optical clock using atoms confined in a lattice. We show that site-to-site tunnelling leads to a residual sensitivity to the atom dynamics hence requiring large depths (50 to $100 E\_r$ for Sr) to avoid any frequency shift or line broadening of the atomic transition at the $10^{-17}-10^{-18}$ level. Such large depths and the corresponding laser power may, however, lead to difficulties (e.g. higher order light shifts, two-photon ionization, technical difficulties) and therefore one would like to operate the clock in much shallower traps. To circumvent this problem we propose the use of an accelerated lattice. Acceleration lifts the degeneracy between adjacents potential wells which strongly inhibits tunnelling. We show that using the Earth's gravity, much shallower traps (down to $5 E\_r$ for Sr) can be used for the same accuracy goal.

physics.atom-ph↗

arXiv2005

Accurate spectroscopy of Sr atoms

We report the frequency measurement with an accuracy in the 100 kHz range of several optical transitions of atomic Sr : $^1S_0- ^3P_1$ at 689 nm, $^3P_1- ^3S_1$ at 688 nm and $^3P_0- ^3S_1$ at 679 nm. Measurements are performed with a frequency chain based on a femtosecond laser referenced to primary frequency standards. They allowed the indirect determination with a 70 kHz uncertainty of the frequency of the doubly forbidden $5s^2^1S_0- 5s5p^3P_0$ transition of $^{87}$Sr at 698 nm and in a second step its direct observation. Frequency measurements are performed for $^{88}$Sr and $^{87}$Sr, allowing the determination of $^3P_0$, $^3P_1$ and $^3S_1$ isotope shifts, as well as the $^3S_1$ hyperfine constants.

physics.atom-ph↗