Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2311.13503

Non-Gaussian correlations in the steady-state of driven-dissipative clouds of two-level atoms

Giovanni Ferioli, Sara Pancaldi, Antoine Glicenstein, David Clément, Antoine Browaeys, Igor Ferrier-Barbut

Published Nov 22, 2023• 0 citations
arXivHTMLPDF

Abstract

We report experimental measurements of the second-order coherence function $g^{(2)}(τ)$ of the light emitted by a laser-driven dense ensemble of $^{87}$Rb atoms. We observe a clear departure from the Siegert relation valid for Gaussian chaotic light. Measuring intensity and first-order coherence, we conclude that the violation is not due to the emergence of a coherent field. This indicates that the light obeys non-Gaussian statistics, stemming from non-Gaussian correlations in the atomic medium. More specifically, the steady-state of this driven-dissipative many-body system sustains high-order correlations in the absence of first-order coherence. These findings call for new theoretical and experimental explorations to uncover their origin and they open new perspectives for the realization of non-Gaussian states of light.

DOI
10.48550/arxiv.2311.13503

Related papers

Steady-state properties of a driven atomic ensemble with nonlocal dissipation

Beatriz Olmos, Deshui Yu, Igor Lesanovsky

In a driven dense ensemble of two-level atoms the decay acts in a correlated way on several atoms simultaneously. The competition between the coherent laser excitation and the dipole-dipole interaction induced by the dissipation gives rise to a bimodal distribution of the excitation density. More interestingly, the presence of nonlocal dissipation lifts the direct connection between the photon emission rate and the density of excited atoms present in typical open atomic systems formed by, for example, Rydberg gases or trapped ions. In contrast, here the bimodality present in the excitation density distribution, which indicates the existence of a dynamical first-order transition, is not accompanied by an intermittent behavior of the photon emission. Moreover, due to the nonlocal character of the dissipation the spatial coherence of the steady state can be measured experimentally by analyzing solely global quantities---the mean values of the photon emission rate and the density of excited atoms. We show that these effects can be experimentally probed in a system of trapped Sr atoms.

arXiv:1308.3967•Physical Review A•Feb 14, 2014•34 citations

Coherent scattering of near-resonant light by a dense, microscopic cloud of cold two-level atoms: Experiment versus theory

Stephan Jennewein, Ludovic Brossard, Yvan R. P. Sortais +4 more

We measure the coherent scattering of low-intensity, near-resonant light by a cloud of laser-cooled two-level rubidium atoms with a size comparable to the wavelength of light. We isolate a two-level atomic structure by applying a 300-G magnetic field. We measure both the temporal and the steady-state coherent optical response of the cloud for various detunings of the laser and for atom numbers ranging from 5 to 100. We compare our results to a microscopic coupled-dipole model and to a multimode, paraxial Maxwell-Bloch model. In the low-intensity regime, both models are in excellent agreement, thus validating the Maxwell-Bloch model. Comparing to the data, the models are found in very good agreement for relatively low densities ($n/{k}^{3}\ensuremath{\lesssim}0.1$), while significant deviations start to occur at higher density. This disagreement indicates that light scattering in dense, cold atomic ensembles is still not quantitatively understood, even in pristine experimental conditions.

arXiv:1802.03563•Physical Review A•May 15, 2018•79 citations

Emergence of Second-Order Coherence in the Superradiant Emission from a Free-Space Atomic Ensemble

Giovanni Ferioli, Igor Ferrier-Barbut, Antoine Browaeys

We investigate the evolution of the second-order temporal coherence during the emission of a superradiant pulse by an elongated cloud of cold Rb atoms in free space. To do so, we measure the two-times intensity correlation function g_{N}^{(2)}(t_{1},t_{2}) following the pulsed excitation of the cloud. By monitoring g_{N}^{(2)}(t,t) during the pulse, we observe the establishment of second-order coherence, and contrast it with the situation where the cloud is initially prepared in a steady state. We compare our findings to the predictions of the Dicke model, using an effective atom number to account for finite size effects, finding that the model reproduces the observed trend at early time. For longer times, we observe a subradiant decay, a feature that goes beyond Dicke's model. Finally, we measure the g_{N}^{(2)}(t_{1},t_{2}) at different times and observe the appearance of anticorrelations during the pulse that are not present when starting from a steady state.

arXiv:2410.08652•Physical Review Letters•Apr 15, 2025•19 citations

Statistical properties of the light scattered by a two-level atom driven by a resonant multimode laser beam

Martine Le Berre, Elisabeth Ressayre, Andree A. Tallet

A theory is presented of the near-resonant interaction of two-level atom with strong Gaussian fields. Analytical expressions are given for the fluorescence intensity and for the two-time first- and second-order correlation functions of the intensity in both cases of a chaotic field and a real Gaussian field. The usual three-peak structure in the fluorescence spectrum is found to disappear because the amplitude fluctuations of the driving light prevent the nutation process. The scattered intensity is shown no longer to present a Markovian character when the atom is driven by a Gaussian field. The atom gains a sort of memory because of the intensity fluctuations in the driving field.

Physical Review A•Jul 1, 1980•14 citations

Correlations and dynamics of tunnel-coupled one-dimensional Bose gases

Thomas Schweigler

We present a series of experiments performed with two ultracold one-dimensional Bose gases (rubidium atoms) in a double well potential. Employing matter-wave interference, we can measure the spatially resolved phase difference between the two gases and consequently investigate spatial correlations. By investigating whether higher order correlation functions can be factorized into correlations of lower order, we can investigate the interaction properties of the system. For a non-interacting system, all correlation functions with orders greater than two factorize and one observes Gaussian fluctuations. Here, we present the measurement of non-factorizing fourth-order correlation functions, leading to an experimental characterization of the interactions between the collective excitations of the quantum many-body system. The degree of non-factorizibility, i.e., the degree of non-Gaussianity of the phase fluctuations, depends on the tuneable tunneling strength between the wells. Starting from such a non-Gaussian state, we are able to observe the dynamical evolution towards a state with factorizing correlation functions (Gaussian fluctuations). We start in a double well with tunneling and then abruptly decouple the two subsystems. Subsequently, we observe how the initially non-Gaussian phase fluctuations become Gaussian. Moreover, we discuss the dynamical emergence of phase coherence in a double well potential with tunneling. We experimentally investigate the evolution starting from two different initial states. In one case, we split a cloud of atoms into two and trigger global oscillations in their relative phase. The oscillations subsequently damp and phase coherence sets in. In the other case, two independent clouds are suddenly coupled by tunneling. Again, phase coherence emerges between the two subsystems.

arXiv:1908.00422•Aug 1, 2019•18 citations

Emission characteristics of laser-driven dissipative coupled-cavity systems

Michael Knap, Enrico Arrigoni, Wolfgang von der Linden +1 more

We consider a laser-driven and dissipative system of two coupled cavities with Jaynes-Cummings nonlinearity. In particular, we investigate both incoherent and coherent laser driving, corresponding to different experimental situations. We employ Arnoldi time evolution as a numerical tool to solve exactly the many-body master equation describing the nonequilibrium quantum system. We evaluate the fluorescence spectrum and the spectrum of the second-order correlation function of the emitted light field. Finally, we relate the measured spectra of the dissipative quantum system to excitations of the corresponding nondissipative quantum system. Our results demonstrate how to interpret spectra obtained from dissipative quantum systems and specify what information is contained therein.

arXiv:1011.2760•Physical Review A•Feb 24, 2011•54 citations
We report experimental measurements of the second-order coherence function g(2)(τ)g^{(2)}(τ)g(2)(τ) of the light emitted by a laser-driven dense ensemble of 87^{87}87Rb atoms. We observe a clear departure from the Siegert relation valid for Gaussian chaotic light. Measuring intensity and first-order coherence, we conclude that the violation is not due to the emergence of a coherent field. This indicates that the light obeys non-Gaussian statistics, stemming from non-Gaussian correlations in the atomic medium. More specifically, the steady-state of this driven-dissipative many-body system sustains high-order correlations in the absence of first-order coherence. These findings call for new theoretical and experimental explorations to uncover their origin and they open new perspectives for the realization of non-Gaussian states of light.
In a driven dense ensemble of two-level atoms the decay acts in a correlated way on several atoms simultaneously. The competition between the coherent laser excitation and the dipole-dipole interaction induced by the dissipation gives rise to a bimodal distribution of the excitation density. More interestingly, the presence of nonlocal dissipation lifts the direct connection between the photon emission rate and the density of excited atoms present in typical open atomic systems formed by, for example, Rydberg gases or trapped ions. In contrast, here the bimodality present in the excitation density distribution, which indicates the existence of a dynamical first-order transition, is not accompanied by an intermittent behavior of the photon emission. Moreover, due to the nonlocal character of the dissipation the spatial coherence of the steady state can be measured experimentally by analyzing solely global quantities---the mean values of the photon emission rate and the density of excited atoms. We show that these effects can be experimentally probed in a system of trapped Sr atoms.
We measure the coherent scattering of low-intensity, near-resonant light by a cloud of laser-cooled two-level rubidium atoms with a size comparable to the wavelength of light. We isolate a two-level atomic structure by applying a 300-G magnetic field. We measure both the temporal and the steady-state coherent optical response of the cloud for various detunings of the laser and for atom numbers ranging from 5 to 100. We compare our results to a microscopic coupled-dipole model and to a multimode, paraxial Maxwell-Bloch model. In the low-intensity regime, both models are in excellent agreement, thus validating the Maxwell-Bloch model. Comparing to the data, the models are found in very good agreement for relatively low densities ($n/{k}^{3}\ensuremath{\lesssim}0.1$), while significant deviations start to occur at higher density. This disagreement indicates that light scattering in dense, cold atomic ensembles is still not quantitatively understood, even in pristine experimental conditions.
We investigate the evolution of the second-order temporal coherence during the emission of a superradiant pulse by an elongated cloud of cold Rb atoms in free space. To do so, we measure the two-times intensity correlation function g_{N}^{(2)}(t_{1},t_{2}) following the pulsed excitation of the cloud. By monitoring g_{N}^{(2)}(t,t) during the pulse, we observe the establishment of second-order coherence, and contrast it with the situation where the cloud is initially prepared in a steady state. We compare our findings to the predictions of the Dicke model, using an effective atom number to account for finite size effects, finding that the model reproduces the observed trend at early time. For longer times, we observe a subradiant decay, a feature that goes beyond Dicke's model. Finally, we measure the g_{N}^{(2)}(t_{1},t_{2}) at different times and observe the appearance of anticorrelations during the pulse that are not present when starting from a steady state.
A theory is presented of the near-resonant interaction of two-level atom with strong Gaussian fields. Analytical expressions are given for the fluorescence intensity and for the two-time first- and second-order correlation functions of the intensity in both cases of a chaotic field and a real Gaussian field. The usual three-peak structure in the fluorescence spectrum is found to disappear because the amplitude fluctuations of the driving light prevent the nutation process. The scattered intensity is shown no longer to present a Markovian character when the atom is driven by a Gaussian field. The atom gains a sort of memory because of the intensity fluctuations in the driving field.
We present a series of experiments performed with two ultracold one-dimensional Bose gases (rubidium atoms) in a double well potential. Employing matter-wave interference, we can measure the spatially resolved phase difference between the two gases and consequently investigate spatial correlations. By investigating whether higher order correlation functions can be factorized into correlations of lower order, we can investigate the interaction properties of the system. For a non-interacting system, all correlation functions with orders greater than two factorize and one observes Gaussian fluctuations. Here, we present the measurement of non-factorizing fourth-order correlation functions, leading to an experimental characterization of the interactions between the collective excitations of the quantum many-body system. The degree of non-factorizibility, i.e., the degree of non-Gaussianity of the phase fluctuations, depends on the tuneable tunneling strength between the wells. Starting from such a non-Gaussian state, we are able to observe the dynamical evolution towards a state with factorizing correlation functions (Gaussian fluctuations). We start in a double well with tunneling and then abruptly decouple the two subsystems. Subsequently, we observe how the initially non-Gaussian phase fluctuations become Gaussian. Moreover, we discuss the dynamical emergence of phase coherence in a double well potential with tunneling. We experimentally investigate the evolution starting from two different initial states. In one case, we split a cloud of atoms into two and trigger global oscillations in their relative phase. The oscillations subsequently damp and phase coherence sets in. In the other case, two independent clouds are suddenly coupled by tunneling. Again, phase coherence emerges between the two subsystems.
We consider a laser-driven and dissipative system of two coupled cavities with Jaynes-Cummings nonlinearity. In particular, we investigate both incoherent and coherent laser driving, corresponding to different experimental situations. We employ Arnoldi time evolution as a numerical tool to solve exactly the many-body master equation describing the nonequilibrium quantum system. We evaluate the fluorescence spectrum and the spectrum of the second-order correlation function of the emitted light field. Finally, we relate the measured spectra of the dissipative quantum system to excitations of the corresponding nondissipative quantum system. Our results demonstrate how to interpret spectra obtained from dissipative quantum systems and specify what information is contained therein.