Polariton Fluids as Quantum Field Theory Simulators on Tailored Curved Spacetimes.

Quantum field theory (QFT) in curved spacetimes predicts the amplification of field excitations and the occurrence of classical and quantum correlations, as in the Hawking effect for example. This raises interest in experiments in which the curvature of spacetime can be controlled and amplification measured, as in fluids going from subsonic to supersonic speeds where acoustic excitations are effectively trapped inside an acoustic horizon. Quantum fluctuations of the acoustic field are predicted to yield entangled emission across the horizon, as in black holes.

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 a 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.

Spin and Density Modes in a Binary Fluid of Light.

We report 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 realized by propagating the two circular polarization components of a laser through a nonlinear hot atomic vapor in the paraxial limit. By controlling the intensity and phase of both polarizations, we selectively excite the fundamental modes of the mixture.

Room-Temperature Efficient Single-Photon Generation from CdSe/ZnS Nanoplatelets.

In the search for materials for quantum information science applications, colloidal semiconductor nanoplatelets (NPLs) have emerged as a highly promising class of materials due to their interesting optical properties, such as narrow emission line widths and fast photoluminescence (PL) lifetimes at room temperature. So far, only a 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 an 8 × 20 nm surface area and 1 nm shell.

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 quantum computing to quantum key distribution to quantum metrology. Among solid-state quantum emitters, colloidal lead halide perovskite (LHP) nanocrystals (NCs) have attracted considerable interest due to their structural and optical properties, which make them attractive candidates for single-photon sources (SPSs). However, their practical utilization has been hampered by environment-induced instabilities.

Nonequilibrium Prethermal States in a Two-Dimensional Photon Fluid.

We report on the observation of a prethermal state in a nonequilibrium, two-dimensional fluid of light. Direct measurements of the first order coherence function of the fluid reveal the dynamical emergence of algebraic correlations, a quasi-steady-state with properties close to those of thermal superfluids. By a controlled increase of the fluctuations, we observe a crossover from algebraic to short-range (exponential) correlations.

Analogue cosmological particle creation in an ultracold quantum fluid of light.

The rapid expansion of the early universe resulted in the spontaneous production of cosmological particles from vacuum fluctuations, some of which are observable today in the cosmic microwave background anisotropy. The analogue of cosmological particle creation in a quantum fluid was proposed, but the quantum, spontaneous effect due to vacuum fluctuations has not yet been observed. Here we report the spontaneous creation of analogue cosmological particles in the laboratory, using a quenched 3-dimensional quantum fluid of light.

Dissipative Phase Transition with Driving-Controlled Spatial Dimension and Diffusive Boundary Conditions.

We investigate theoretically and experimentally a first-order dissipative phase transition, with diffusive boundary conditions and the ability to tune the spatial dimension of the system. The considered physical system is a planar semiconductor microcavity in the strong light-matter coupling regime, where polariton excitations are injected by a quasiresonant optical driving field. The spatial dimension of the system from 1D to 2D is tuned by designing the intensity profile of the driving field.

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

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, S(k), 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.

Attenuation-free non-diffracting Bessel beams.

We report on a versatile method to compensate the linear attenuation in a medium, independently of its microscopic origin. The method exploits diffraction-limited Bessel beams and tailored on-axis intensity profiles, which are generated using a phase-only spatial light modulator. This technique for compensating one of the most fundamental limiting processes in linear optics is shown to be efficient for a wide range of experimental conditions (modifying the refractive index and the attenuation coefficient).

Complete polarization control for a nanofiber waveguide using the scattering properties.

We report on a protocol to achieve full control of the polarization in a nanofiber. The protocol relies on monitoring the light scattered out from a nanofiber by means of two optical systems with 45° camera angle difference. We study the disturbance of the nanofiber refractive index on the radiation of embedded scatterers, and we propose an explanation for the observed reduced scattering contrast of the nanofiber.

Imaging light scattered by a subwavelength nanofiber, from near field to far field.

We present a direct experimental investigation of the optical field distribution around a suspended tapered optical nanofiber by means of a fluorescent scanning probe. Using a 100 nm diameter fluorescent bead as a probe of the field intensity, we study interferences made by a nanofiber (400 nm diameter) scattering a plane wave (568 nm wavelength). Our scanning fluorescence near-field microscope maps the optical field over 36 μm, with λ/5 resolution, from contact with the surface of the nanofiber to a few micrometers away.

Localised excitation of a single photon source by a nanowaveguide.

Nowadays, integrated photonics is a key technology in quantum information processing (QIP) but achieving all-optical buses for quantum networks with efficient integration of single photon emitters remains a challenge. Photonic crystals and cavities are good candidates but do not tackle how to effectively address a nanoscale emitter. Using a nanowire nanowaveguide, we realise an hybrid nanodevice which locally excites a single photon source (SPS).

Exciton Fine Structure of CdSe/CdS Nanocrystals Determined by Polarization Microscopy at Room Temperature.

We present a method that allows determining the band-edge exciton fine structure of CdSe/CdS dot-in-rods samples based on single particle polarization measurements at room temperature. We model the measured emission polarization of such single particles considering the fine structure properties, the dielectric effect induced by the anisotropic shell, and the measurement configuration. We use this method to characterize the band-edge exciton fine structure splitting of various samples of dot-in-rods.

Temporally multiplexed storage of images in a gradient echo memory.

We study the storage and retrieval of images in a hot atomic vapor using the gradient echo memory protocol. We demonstrate that this technique allows for the storage of multiple spatial modes. We study both spatial and temporal multiplexing by storing a sequence of two different images in the atomic vapor.