Measurement of the Static Structure Factor in a Paraxial Fluid of Light Using Bragg-like Spectroscopy

Abstract

We implement Bragg-like spectroscopy in a paraxial fluid of light by imprinting analogues of short Bragg pulses on the photon fluid using wavefront shaping with a spatial light modulator. We report a measurement of the static structure factor, SðkÞ, and we find a quantitative agreement with the prediction of the Feynman relation revealing indirectly the presence of pair-correlated particles in the fluid. Finally, we improve the resolution over previous methods and obtain the dispersion relation including a linear phononic regime for weakly interacting photons and low sound velocity.

Non-equilibrium pre-thermal states in a two-dimensional photon fluid

“…7 are shown together with the theoretical calculation, Eq. (30), in which we additionally include the contribution of phonon collisions at short times, by using a phenomenological fit correction term β within the square brackets, as explained in [1]. This leads to a very good agreement with the numerical data, confirming the validity of our approach and, in particular, the use of a local density approximation.…”

“…In parallel, fluids of light in the propagating geometry [27] have emerged as a complementary platform to study 2D Bose gases, with the observation of Bogoliubovlike dispersion [28][29][30][31], signatures of photon condensation [32,33] and spontaneous nucleation of vortices in a photonic lattice [34]. This platform relies on the formal analogy between a laser field propagating through a nonlinear medium and the temporal evolution of a 2D quantum fluid.…”

Analogue cosmological particle creation in an ultracold quantum fluid of light

“…For the second quench, the thermal component does not diverge like since the zero-temperature static structure factor in the fluid of light goes to zero for low (Ref. 31 ).…”

Onset of vortex clustering and inverse energy cascade in dissipative quantum fluids

“…Importantly, we can decouple the compressible and incompressible contributions to the kinetic energy, showing that the energy required to start the clusterization dynamics is provided to the vortex gas by the dissipation of sound waves. Finally, we show that the optical measurement of the velocity field allows an unprecedented control over the dynamics of the vortex gas, enabling a new series of experiments to be performed in nonlinear optical systems such as semiconductor microcavities, nonlinear crystals and laser beams coupled to hot atomic vapours or Rydberg atomic states [45][46][47][48].…”