arXiv subjects

Quentin Glorieux

Publications and source records attributed to Quentin Glorieux.

At least 19 recordsLinked to original sources

arXiv2025

Swimming against a superfluid flow: Self-propulsion via vortex-antivortex shedding in a quantum fluid of light

A superfluid flows without friction below a critical velocity, exhibiting zero drag force on impurities. Above this threshold, superfluidity breaks down, and the internal energy is redistributed into incoherent excitations such as vortices. We demonstrate that a finite-mass, mobile impurity immersed in a flowing two-dimensional paraxial superfluid of light can \textit{swim} against the superfluid current when this critical velocity is exceeded. This self-propulsion is achieved by the periodic emission of quantized vortex-antivortex pairs downstream, which impart an upstream recoil momentum that results in a net propulsive force. Analogous to biological systems that minimize effort by exploiting wake turbulence, the impurity harnesses this vortex backreaction as a passive mechanism of locomotion. Reducing the impurity dynamics to the motion of its center of mass and using a point-vortex model, we quantitatively describe how this mechanism depends on the impurity geometry and the surrounding flow velocity. Our findings establish a fundamental link between internal-energy dissipation in quantum fluids and concepts of self-propulsion in active-matter systems, and opens new possibilities for exploiting vortices for controlled quantum transport at the microscale.

cond-mat.quant-gas↗

arXiv2025

Vortex leapfrogging and superfluid dissipation mechanisms in a fluid of light

We report the experimental observation of vortex leapfrogging in a two-dimensional fluid of light. By imprinting two vortex-antivortex pairs and tracking their real-time evolution through phase-resolved imaging, we observe a dynamics that is accurately described by a point-vortex model with an outward background flow. By precisely controlling the initial vortex separation, we identify configurations in which leapfrogging breaks down and determine the corresponding dissipation mechanisms. The first originates from phase-slip events occurring at large injected velocities. The second arises when the injection of multi-charged vortices leads to the formation of a dispersive shock wave which acts as a continuous source of phase slippage. These mechanisms advance our understanding of vortex dynamics and dissipation in superfluids.

cond-mat.quant-gas↗

arXiv2025

Measuring the group velocity dispersion in near resonant hot atomic vapors

Group velocity dispersion (GVD) in near-resonant hot atomic vapors is difficult to measure with standard pulse broadening or interferometric techniques, as absorption, pulse distortion and nonlinearities strongly affect the probe and reduce the signal-to-noise ratio. We introduce a simpler method using a continuous-wave laser with weak phase modulation and a slow photodetector, directly inspired by Bragg-like spectroscopy in fluids of light. During propagation, the red and blue-detuned sidebands accumulate different dispersive phase shifts, leading to oscillations in the transmitted modulation contrast as the modulation frequency is scanned. Vanishing contrast at well-defined frequencies directly yields the GVD. We apply this technique to hot rubidium vapors and observe the strong frequency dependence of the GVD across a broad detuning range of the D2 line at different temperatures.

physics.optics↗

arXiv2025

Machine learning approach to single-shot multiparameter estimation for the non-linear Schrödinger equation

The nonlinear Schrödinger equation (NLSE) is a fundamental model for wave dynamics in nonlinear media ranging from optical fibers to Bose-Einstein condensates. Accurately estimating its parameters, which are often strongly correlated, from a single measurement remains a significant challenge. We address this problem by treating parameter estimation as an inverse problem and training a neural network to invert the NLSE mapping. We combine a fast numerical solver with a machine learning approach based on the ConvNeXt architecture and a multivariate Gaussian negative log-likelihood loss function. From single-shot field (density and phase) images, our model estimates three key parameters: the nonlinear coefficient $n_2$, the saturation intensity $I_{sat}$, and the linear absorption coefficient $α$. Trained on 100,000 simulated images, the model achieves a mean absolute error of $3.22\%$ on 12,500 unseen test samples, demonstrating strong generalization and close agreement with ground-truth values. This approach provides an efficient route for characterizing nonlinear systems and has the potential to bridge theoretical modeling and experimental data when realistic noise is incorporated.

quant-ph↗

arXiv2025

Paraxial fluids of light

Paraxial fluids of light are a promising platform for exploring collective phenomena in a highly tunable environment. These systems, which map the propagation of light through nonlinear media onto the wavefunction of effective 2D quantum fluids, offer a complementary approach to traditional platforms such as cold atomic gases or superfluid helium. In this review, we present a detailed overview of the theoretical framework underlying paraxial fluids of light, including the nonlinear Schrödinger equation (NLSE) and its mapping to the 2D+1 Gross-Pitaevskii equation (GPE). We explore the hydrodynamic formulation of these systems and we provide a comparative analysis of fluids of light and cold atomic gases, examining key parameters and figures of merit. We then review the recent experimental advances and the experimental platforms currently used to realize paraxial fluids of light, including hot atomic vapors, photorefractive crystals, and thermo-optic media. Additionally, we question the geometry of the system extending the analogy from 2D+1 to lower or higher dimensions. Looking forward, we outline the potential future directions for the field, including the use of laser cooled atoms as nonlinear media, the study of two-component mixtures, and the exploration of quantum effects beyond the mean-field approximation. These developments promise to deepen our understanding of quantum fluids and potentially contribute to advances in quantum technologies.

cond-mat.quant-gas↗

arXiv2025

Observation of Jones-Roberts solitons in a paraxial quantum fluid of light

We investigate the formation and dynamics of Jones-Roberts solitons in a smoothly inhomogeneous quantum fluid. To do so, we create a superfluid of light using paraxial, near-resonant laser beam propagating through a hot rubidium vapor. We excite a bounded vortex-antivortex dipole in the superfluid and observe its transition to a rarefaction pulse and back, in agreement with the seminal predictions of Jones and Roberts. Employing an analogy with ray optics, we calculate the trajectory of the interacting vortices, deriving an effective refractive index from the inhomogeneous fluid density. Finally, we examine analytically and experimentally the superfluid velocity correlations, observing a transfer of coherence from incompressible to compressible velocity of the quantum fluid, a direct signature of the dynamical conversion between vortices and rarefaction pulse.

cond-mat.quant-gas↗

arXiv2025

Spin and Density Modes in a Binary Fluid of Light

We present the experimental observation of spin and density modes in a binary mixture of superfluids of light. A miscible Bose-Bose mixture with repulsive interactions is obtained by propagating, in the paraxial limit, the two circular polarization components of a laser through a non-linear hot atomic vapor. Controlling the intensity and phase for both polarizations allows us to selectively excite the fundamental modes of the mixture. Using a Bragg-like spectroscopy technique, we measure the dispersion relation and identify two distinct branches with different speeds of sound corresponding to the spin and density modes. At large photon density, we observe a crossing of these branches, which is due to an effective photon-photon interaction beyond the two-body regime and related to the saturation of the medium nonlinearity. This novel degree of freedom allows for precise control over the ratio of spin and density sound velocities and provide new insights into the control of binary mixtures collective dynamics.

cond-mat.quant-gas↗

arXiv2024

Room-temperature efficient single-photon generation from CdSe/ZnS nanoplateletes

In the search for materials for quantum information science applications, colloidal semiconductor nanoplatelets (NPLs) have emerged as a highly promising new class of materials due to their interesting optical properties, such as narrow emission linewidth and fast photoluminescence (PL) lifetimes at room temperature. So far only few works focused on the quantum properties of their emission, however, NPLs, with their atomic-scale thickness and one-dimensional quantum confinement, are promising candidates for single-photon sources. Here, we demonstrate room-temperature single-photon emission from core/shell CdSe/ZnS NPLs, which feature 8$x$20 nm$^2$ surface area and 1 nm shell. The limited surface area ensures effective Auger non-radiative recombination, resulting in highly efficient single-photon generation with values of photon purity as low as $g^{(2)}(τ)=0.04$. The observed long-period blinking and bleaching, typical of such thin shells, can be easily reduced by increasing the shell thickness. This work establishes NPLs as new single-photon sources very well suited for integration into quantum photonic systems.

quant-ph↗

arXiv2023

Turbulent dynamics in two-dimensional paraxial fluid of light

Turbulence in quantum fluids has, surprisingly, a lot in common with its classical counterpart. Recently, cold atomic gases has emerged as a well controlled experimental platform to study turbulent dynamics. In this work, we introduce a novel system to study quantum turbulence in optics, with the major advantage of having access to a wide range of characterization tools available for light fields. In particular we report the temporal dynamics of density and phase and we show the emergence of isotropy in momentum space and the presence of different scaling laws in the incompressible kinetic energy spectrum. The microscopic origin of the algebraic exponents in the energy spectrum is discussed by studying the internal structure of quantized vortices within the healing length and their clustering at larger length scales. These results are obtained using two counter-streaming fluids of light, which allows for a precise preparation of the initial state and the in-situ measurement of the compressible and incompressible fluid velocity.

cond-mat.quant-gas↗

arXiv2023

Polariton Fluids as Quantum Field Theory Simulators on Tailored Curved Spacetimes

Quantum fields in curved spacetime exhibit a wealth of effects like Hawking radiation from black holes. While quantum field theory in black holes can only be studied theoretically, it can be tested in controlled laboratory experiments. In experiments, a fluid going from sub- to supersonic speed creates an effectively curved spacetime for the acoustic field, with a horizon where the speed of the fluid equals the speed of sound. The challenge to test predictions like the Hawking effect in such systems lies in the control of the spacetime curvature and access to the field spectrum thereon. Here, we create tailored stationary effective curved spacetimes in a polaritonic quantum fluid of light in which either massless or massive excitations can be created, with smooth and steep horizons and various supersonic fluid speeds. Using a recently developed spectroscopy method we measure the spectrum of collective excitations on these spacetimes, crucially observing negative energy modes in the supersonic regions, which signals the formation of a horizon. Control over the horizon curvature and access to the spectrum on either side demonstrates the potential of quantum fluids of light for the study of field theories on curved spacetimes, and we discuss the possibility of investigating emission and spectral instabilities with a horizon or in an effective Exotic Compact Object configuration.

cond-mat.quant-gas↗

arXiv2023

Observation of the diffusive Nambu-Goldstone mode of a non-equilibrium phase transition

Second-order phase transitions are governed by spontaneous symmetry breaking, which yield collective excitations with a gapless spectrum called Nambu-Goldstone (NG) modes. While NG modes in conservative systems are propagating excitations, non-equilibrium phase transitions have been predicted to feature a diffusive NG mode. We present the first experimental evidence of a diffusive NG mode in a non-equilibrium Bose-Einstein condensate of microcavity polaritons. The NG mode is observed as a spectral narrowing in the spectroscopic response of the condensate. Additionally, explicitly breaking the symmetry causes the opening of a gap in the spectrum and the disappearance of the NG mode. Our observations confirm the diffusive dynamics of the NG mode of non-equilibrium phase transitions and establish a promising framework to investigate fundamental questions in statistical mechanics.

cond-mat.quant-gas↗

arXiv2023

Highly photostable Zn-treated halide perovskite nanocrystals for efficient single photon generation

Achieving pure single-photon emission is essential for a range of quantum technologies, from optical quantum computing to quantum key distribution to quantum metrology. Among solid-state quantum emitters, colloidal lead halide perovskite (LHP) nanocrystals (NCs) have garnered significant attention due to their interesting structural and optical properties, which make them appealing single-photon sources (SPSs). However, their practical utilization for quantum technology applications has been hampered by environment-induced instabilities. In this study, we fabricate and characterize in a systematic manner Zn-treated $CsPbBr_3$ colloidal NCs obtained through $Zn^{2+}$ ion doping at the Pb-site, demonstrating improved stability under dilution and illumination. These doped NCs exhibit high single-photon purity, reduced blinking on a sub-millisecond timescale and stability of the bright state for excitation powers well above the saturation levels. Our findings highlight the potential of this synthesis approach to optimize the performance of LHP-based SPSs, opening up interesting prospects for their integration into nanophotonic systems for quantum technology applications.

quant-ph↗

arXiv2023

Quantum vacuum excitation of a quasi-normal mode in an analog model of black hole spacetime

Vacuum quantum fluctuations near horizons are known to yield correlated emission by the Hawking effect. We use a driven-dissipative quantum fluid of microcavity polaritons as an analog model of a quantum field theory on a black-hole spacetime and numerically calculate correlated emission. We show that, in addition to the Hawking effect at the sonic horizon, quantum fluctuations may result in a sizeable stationary excitation of a quasi-normal mode of the field theory. Observable signatures of the excitation of the quasi-normal mode are found in the spatial density fluctuations as well as in the spectrum of Hawking emission. This suggests an intrinsic fluctuation-driven mechanism leading to the quantum excitation of quasi-normal modes on black hole spacetimes.

gr-qc↗

arXiv2022

Spectrum of collective excitations of a quantum fluid of polaritons

We use a recently developed high-resolution coherent probe spectroscopy method to investigate the dispersion of collective excitations of a polaritonic quantum fluid. We measure the dispersion relation with high energy and wavenumber resolution, which allows us to determine the speed of sound in the fluid and to evidence the contribution of an excitonic reservoir. We report on the generation of collective excitations at negative energies, on the ghost branch of the dispersion curve. Precursors of dynamical instabilities are also identified. Our methods open the way to the precise study of quantum hydrodynamics of quantum fluids of light.

cond-mat.quant-gas↗

arXiv2022

Hot atomic vapors for nonlinear and quantum optics

Nonlinear optics has been a very dynamic field of research with spectacular phenomena discovered mainly after the invention of lasers. The combination of high intensity fields with resonant systems has further enhanced the nonlinearity with specific additional effects related to the resonances. In this paper we review a limited range of these effects which has been studied in the past decades using close-to-room-temperature atomic vapors as the nonlinear resonant medium. In particular we describe four-wave mixing (4WM) and generation of nonclassical light in atomic vapors. One-and two-mode squeezing as well as photon correlations are discussed. Furthermore, we present some applications for optical and quantum memories based on hot atomic vapors. Finally, we present results on the recently developed field of quantum fluids of light using hot atomic vapors.

quant-ph↗

arXiv2022

Color-Tunable Mixed-Cation Perovskite Single Photon Emitters

Quantum photonics technologies like wavelength division multiplexing (WDM) for high-rate quantum key distribution require narrowband, spectrally tunable single photon emitters. Physical methods that rely on the application of large mechanical strain to epitaxial quantum dots or electric and magnetic fields to color centers in 2D metal dichalcogenides provide limited spectral tunability. Here we adopt a chemical approach to synthesize a family of colloidal mixed-cation perovskite quantum dots ($\text{Cs}_{1-x}\text{FA}_{x}\text{PbBr}_3$) that show highly photo-stable, compositionally tunable single photon emission at room temperature - spanning more than 30 nm in the visible wavelength spectral range. We find that, tailoring the stoichiometry of the organic formamidinium (FA) cation in all-inorganic cesium lead bromide ($\text{CsPbBr}_3$) perovskite quantum dots detunes the electronic band structure while preserving their excellent single photon emission characteristics. We argue that the mixed-cation perovskite quantum dots studied in this work offer a new platform for the realization of color-tunable single photon emitters that could be readily integrated in a diversity of quantum photonic devices.

quant-ph↗

arXiv2022

Analogue quantum simulation of the Hawking effect in a polariton superfluid

Quantum effects of fields on curved spacetimes may be studied in the laboratory thanks to quantum fluids. Here we use a polariton fluid to study the Hawking effect, the correlated emission from the quantum vacuum at the acoustic horizon. We show how out-of-equilibrium physics affects the dispersion relation, and hence the emission and propagation of correlated waves: the fluid properties on either side of the horizon are critical to observing the Hawking effect. We find that emission may be optimised by supporting the phase and density of the fluid upstream of the horizon in a regime of optical bistability. This opens new avenues for the observation of the Hawking effect in out-of-equilibrium systems as well as for the study of new phenomenology of fields on curved spacetimes.

quant-ph↗

arXiv2022

Transit effects for non-linear index measurement in hot atomic vapors

Hot atomic vapors are widely used in non-linear and quantum optics due to their large Kerr non-linearity. While the linear refractive index and the transmission are precisely measured and well modeled theoretically, similar characterization remains partial for the $χ^{(3)}$ non-linear part of the susceptibility. In this work, we present a set of tools to measure and estimate numerically the non-linear index of hot atomic vapors both in the steady state and during the transient response of the medium. We apply these techniques for the characterization of a hot vapor of rubidium and we evidence the critical role played by transit effects, due to finite beam sizes, in the measurement of the non-linear index.

quant-ph↗