Optomechanical signature of a frictionless flow of superfluid light

We propose an experimental setup that should make it possible to reveal the frictionless flow of a superfluid of light from the suppression of the drag force that it exerts onto a material obstacle. In the paraxial-propagation geometry considered here, the photon-fluid dynamics is described by a wave equation analogous to the Gross-Pitaevskii equation of dilute Bose-Einstein condensates and the obstacle consists in a solid dielectric slab immersed into a nonlinear optical liquid. By means of an ab initio calculation of the electromagnetic force experienced by the obstacle, we anticipate that superfluidity is detectable in state-of-the-art experiments from the disappearance of the optomechanical deformation of the obstacle.Comment: 10 pages, 4 figure

Hawking radiation in a two-component Bose-Einstein condensate

We consider a simple realization of an event horizon in the flow of a one-dimensional two-component Bose-Einstein condensate. Such a condensate has two types of quasiparticles; In the system we study, one corresponds to density fluctuations and the other to polarization fluctuations. We treat the case where a horizon occurs only for one type of quasiparticles (the polarization ones). We study the one- and two-body signal associated to the analog of spontaneous Hawking radiation and demonstrate by explicit computation that it consists only in the emission of polarization waves. We discuss the experimental consequences of the present results in the domain of atomic Bose-Einstein condensates and also for the physics of exciton-polaritons in semiconductor microcavities

Postquench prethermalization in a disordered quantum fluid of light

We study the coherence of a disordered and interacting quantum light field after propagation along a nonlinear optical fiber. Disorder is generated by a cross-phase modulation with a randomized auxiliary classical light field, while interactions are induced by self-phase modulation. When penetrating the fiber from free space, the incoming quantum light undergoes a disorder and interaction quench. By calculating the coherence function of the transmitted quantum light, we show that the decoherence induced by the quench spreads in a light-cone fashion in the nonequilibrium many-body quantum system, leaving the latter prethermalize with peculiar features originating from disorder.Comment: 18 pages, 5 figure

Wave pattern induced by a localized obstacle in the flow of a one-dimensional polariton condensate

Motivated by recent experiments on generation of wave patterns by a polariton condensate incident on a localized obstacle, we study the characteristics of such flows under the condition that irreversible processes play a crucial role in the system. The dynamics of a non-resonantly pumped polariton condensate in a quasi-one-dimensional quantum wire is modeled by a Gross-Pitaevskii equation with additional phenomenological terms accounting for the dissipation and pumping processes. The response of the condensate flow to an external potential describing a localized obstacle is considered in the weak-perturbation limit and also in the nonlinear regime. The transition from a viscous drag to a regime of wave resistance is identified and studied in detail

Polarization hydrodynamics in a one-dimensional polariton condensate

We study the hydrodynamics of a nonresonantly-pumped polariton condensate in a quasi-one-dimensional quantum wire taking into account the spin degree of freedom. We clarify the relevance of the Landau criterion for superfluidity in this dissipative two-component system. Two Cherenkov-like critical velocities are identified corresponding to the opening of different channels of radiation: one of (damped) density fluctuations and another of (weakly damped) polarization fluctuations. We determine the drag force exerted onto an external obstacle and propose experimentally measurable consequences of the specific features of the fluctuations of polarization

Propagation of a quantum fluid of light in a cavityless nonlinear optical medium: General theory and response to quantum quenches

Making use of a generalized quantum theory of paraxial light propagation where the radiation-axis and the temporal coordinates play exchanged roles, we discuss the potential of bulk nonlinear optical media in cavityless configurations for quantum statistical mechanics studies of the conservative many-body dynamics of a gas of interacting photons. To illustrate the general features of this point of view, we investigate the response of the fluid of light to the quantum quenches in the photon-photon interaction constant experienced at the front and the back faces of a finite slab of weakly nonlinear material. Extending the standard Bogoliubov theory of dilute Bose-Einstein condensates, peculiar features are predicted for the statistical properties of the light emerging from the nonlinear medium.Comment: 17 pages, 4 figure

Nonlinear waves of polarization in two-component Bose-Einstein condensates

Waves with different symmetries exist in two-component Bose-Einstein condensates (BECs) whose dynamics is described by a system of coupled Gross-Pitaevskii (GP) equations. A first type of waves corresponds to excitations for which the motion of both components is locally in phase. In the second type of waves the two components have a counter-phase local motion. In the case of different values of inter- and intra-component interaction constants, the long wave-length behavior of these two modes corresponds to two types of sound with different velocities. In the limit of weak nonlinearity and small dispersion the first mode is described by the well-known Korteweg-de Vries (KdV) equation. We show that in the same limit the second mode can be described by the Gardner (modified KdV) equation, if the intra-component interaction constants have close enough values. This leads to a rich phenomenology of nonlinear excitations (solitons, kinks, algebraic solitons, breathers) which does not exist in the KdV description.Comment: 10 pages, 5 figure

Pump-and-probe optical transmission phase shift as a quantitative probe of the Bogoliubov dispersion relation in a nonlinear channel waveguide

We theoretically investigate the dispersion relation of small-amplitude optical waves superimposing upon a beam of polarized monochromatic light propagating along a single-mode channel waveguide characterized by an instantaneous and spatially local Kerr nonlinearity. These small luminous fluctuations propagate along the waveguide as Bogoliubov elementary excitations on top of a one-dimensional dilute Bose quantum fluid evolve in time. They consequently display a strongly renormalized dispersion law, of Bogoliubov type. Analytical and numerical results are found in both the absence and the presence of one- and two-photon losses. Silicon and silicon-nitride waveguides are used as examples. We finally propose an experiment to measure this Bogoliubov dispersion relation, based on a stimulated four-wave mixing and interference spectroscopy techniques.Comment: 17 pages, 7 figure

Quantum fluctuations around black hole horizons in Bose-Einstein condensates

We study several realistic configurations allowing to realize an acoustic horizon in the flow of a one dimensional Bose-Einstein condensate. In each case we give an analytical description of the flow pattern, of the spectrum of Hawking radiation and of the associated quantum fluctuations. Our calculations confirm that the non local correlations of the density fluctuations previously studied in a simplified model provide a clear signature of Hawking radiation also in realistic configurations. In addition we explain by direct computation how this non local signal relates to short range modifications of the density correlations