arXiv subjects

Loïc Morvan

Publications and source records attributed to Loïc Morvan.

5 recordsLinked to original sources

arXiv2026

Quantum-enhanced sensing via spectral noise reduction

We report a direct demonstration of quantum-enhanced sensing in the Fourier domain by comparing single- and two-photon interference in a fiber-based interferometer under strictly identical noise conditions. The simultaneous acquisition of both signals provides a common-mode reference that enables a fair and unambiguous benchmark of quantum advantage. Spectral analysis of the interferometric outputs reveals that quantum correlations do not increase the amplitude of the modulation peak, but instead lower the associated noise floor, resulting in the expected 3 dB improvement in signal-to-noise ratio. This enhancement persists in the sub-shot-noise regime, where the classical signal becomes buried in the spectral background while the two-photon contribution remains resolvable. These observations establish Fourier-domain quantum super-sensitivity as an operational and broadly applicable resource for precision interferometric sensing.

quant-ph↗

arXiv2025

Optical investigation of ultra-slow spin relaxation in $^{171}$Yb$^{3+}$:Y$_2$SiO$_5$ single crystals

We present a comprehensive study of spin relaxation dynamics at cryogenic temperatures in a rare-earth-doped crystal used for quantum memory applications: $^{171}$Yb:Y$_2$SiO$_5$. Spin relaxation is indeed a major limiting factor for both the efficiency and storage time of quantum memory protocols based on atomic frequency combs in rare-earth materials. The relaxation dynamics among the four ground-state hyperfine levels were simultaneously investigated by optically perturbing the spin population distribution and monitoring its return to thermal equilibrium through optical absorption spectroscopy. By applying different types of perturbations, we were also able to distinguish between two types of relaxation processes, induced by spin-phonon and spin-spin interactions. Below 1 K, we observed that the re-thermalization of the Yb$^{3+}$ ion population takes several hours, driven solely by direct phonon absorption or emission. However, the effective lifetime of individual spin states is much shorter - on the order of several seconds in low-doped (2 ppm) samples and of milliseconds in 10 ppm samples - due to spin-spin interactions. These findings provide valuable guidelines for optimizing doping levels and operating temperatures in rare-earth-doped crystals for quantum applications. Notably, they suggest that atomic frequency combs with lifetimes of several hours could be realized using $^{171}$Yb:Y$_2$SiO$_5$ crystals with slightly less than 2 ppm doping and operating near 1 K.

physics.atom-ph↗

arXiv2023

Ramsey CPT Signal Generation with a Miniature Clock Bench and a Dual-Frequency Optical Generator

We demonstrate, for the first time, Ramsey CPT spectroscopy with a miniature electro-optical bench associated to a dual-frequency generator based on combined optical injection locking and optical phase locking techniques Preliminary results show Ramsey CPT resonance with a contrast of 2% at the Cesium D2 line. Frequency difference locking loops lead to a contribution of Dick effect to fractional frequency stability lower than 1.7x10-13 at 1 s, in line with targeted clock stability of 5x10-13 at 1 s.

physics.atom-ph↗

arXiv2019

Optomechanical Gigahertz Oscillator made of a Two Photon Absorption free piezoelectric III/V semiconductor

Oscillators in the GHz frequency range are key building blocks for telecommunication, timing and positioning applications. Operating directly in the GHz and compactness while keeping high frequency stability, is still an up-to-date challenge. Recently, optomechanical crystals, compact by nature, have demonstrated GHz frequency modes, thus gathering prerequisite features for using them as oscillators. Here we report on the demonstration, in ambient atmospheric conditions, of an optomechanical oscillator designed with an original concept based on bichromatic one-dimensional optomechanical crystal. Self sustained oscillations directly at 3 GHz are routinely achieved with a low optical power threshold of 40 $μW$ and short-term linewidth narrowed down to 100 Hz in agreement with phase noise measurements (-113 dBc/Hz at 1 MHz from the carrier) for free running optomechanical oscillators. This oscillator is made of InGaP, low loss and TPA-free piezoelectric material which makes it valuable for optomechanics.

physics.optics↗

arXiv2015

Interlaced spin grating for optical wave filtering

Interlaced Spin Grating is a scheme for the preparation of spectro-spatial periodic absorption gratings in a inhomogeneously broadened absorption profile. It relies on the optical pumping of atoms in a nearby long-lived ground state sublevel. The scheme takes advantage of the sublevel proximity to build large contrast gratings with unlimited bandwidth and preserved average optical depth. It is particularly suited to Tm-doped crystals in the context of classical and quantum signal processing. In this paper, we study the optical pumping dynamics at play in an Interlaced Spin Grating and describe the corresponding absorption profile shape in an optically thick atomic ensemble. We show that, in Tm:YAG, the diffraction efficiency of such a grating can reach 18.3% in the small angle, and 11.6% in the large angle configuration when the excitation is made of simple pulse pairs, considerably outperforming conventional gratings.

quant-ph↗