Alberto Bramati

The authors calculate correlations between Hawking radiation, its partner wave inside the horizon, and greybody factors near an acoustic horizon in a driven-dissipative fluid of light. Resolving the correlations in the frequency domain allows one to weigh the contributions of each pair to the total output quantum state

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 mobile, finite-mass impurity immersed in a flowing two-dimensional paraxial superfluid of light can swim against the superfluid current when the critical velocity is exceeded. This self-propulsion is achieved by the periodic emission of 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. Based on a simple theoretical 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 open new possibilities for exploiting quantum vortices for controlled transport at the microscale.

Monitoring local brain temperature with high spatial precision is essential to understanding neurophysiological processes and managing the side effects of optical neuromodulation techniques. We present a novel multifunctional neural interface integrating a microscale resistance temperature detector (µRTD) onto the curved surface of a tapered optical fiber (TF), enabling co‐localized light delivery and thermal sensing with minimal footprint. The µRTD, patterned via an unconventional two‐photon polymerization (TPP)‐based process on the fiber surface, exhibits thermal sensitivity <0.1°C and low self‐heating under physiologically‐safe bias conditions. We demonstrate the system's capacity to resolve subtle temperature changes induced by optogenetic stimulation/inhibition protocols (the latter requiring illumination periods of hundreds of milliseconds up to several seconds), revealing significant thermal accumulation only under long, high‐intensity illumination. This integration resolves the spatial mismatch of multimodal probes and reduces implant cross‐section compared to coaxial or side‐by‐side configurations. Furthermore, the TPP approach is modular, allowing integration with additional functionalities (i.e., electrophysiological recording or thermoplasmonics). By uniting photonic and thermal readout into a minimally invasive probe, our technology offers a powerful tool for studying thermally mediated neural processes, enhancing the safety and interpretability of optical neurotechnologies. Its integration potential positions this platform as a complementary technology for next‐generation multifunctional neural interfaces.

The formation of quantized vortices is a unifying feature of quantum mechanical systems, making it a premier means for fundamental and comparative studies of different quantum fluids. Being excited states of motion, vortices are normally unstable towards relaxation into lower energy states. However, here we exploit the driven-dissipative nature of polaritonic fluids of light to create stationary, multiply charged vortices. We measure the spectrum of collective excitations and observe negative energy modes at the core and positive energy modes at large radii. Their coexistence at the same frequency normally causes the dynamical instability, but here intrinsic losses stabilize the system, allowing for phase pinning by the pump on macroscopic scales. We observe generic features of quantized vortices in quantum fluids and other rotating geometries like astrophysical compact objects, opening the way to the study of generic amplification phenomena.

This study introduces a novel method for the deterministic fabrication of metallic nanostructures with controlled geometry and composition on suspended, single‐mode tapered optical nanofibers (TNFs) using a tailored Blurred Electron Beam Induced Deposition (BEBID) technique. TNFs, owing to their subwavelength diameters and intense evanescent fields, offer a unique platform for enhanced light–matter interactions at the nanoscale. However, their mechanical fragility has thus far hindered the integration of plasmonic structures using conventional high‐energy deposition methods. BEBID addresses this limitation by deliberately defocusing the electron beam to reduce local mechanical stress, minimize vibration, and prevent fiber damage during deposition, thereby enabling the one‐step growth of platinum nanopillars with sub‐20 nm spatial precision and high structural fidelity directly on suspended TNFs. The fabricated structures are characterized using SEM, EDX, and their optical properties are investigated through broadband scattering spectra and polarization‐resolved measurements, showing strong agreement with Finite‐Difference Time‐Domain (FDTD) simulations. Numerical modeling further reveals that ordered arrays of nanopillars can shape and direct the scattered field along the fiber axis, enabling directional emission. This work establishes BEBID as a versatile nanofabrication approach for functional photonic architectures on fragile substrates, with direct applications in quantum photonics, nano‐optics, and on‐fiber plasmonic sensing.

A fluid made of light can simulate a black hole's boundary, providing insights into the mysterious quantum phenomena that occur at such a boundary.

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 nm² surface area and 1 nm shell. The limited surface area ensures effective Auger nonradiative recombination, resulting in highly efficient single-photon generation with values of photon purity as low as g⁽²⁾(0) = 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 single-photon sources that are very well suited for integration into quantum photonic systems.

This study introduces a novel method for the deterministic fabrication of metallic nanostructures with controlled geometry and composition on suspended, single mode tapered optical nanofibers (TNFs) using a tailored Blurred Electron Beam Induced Deposition (BEBID) technique. TNFs, owing to their subwavelength diameters and intense evanescent fields, offer a unique platform for enhanced light matter interactions at the nanoscale. However, their mechanical fragility has thus far hindered the integration of plasmonic structures using conventional high energy deposition methods. BEBID addresses this limitation by deliberately defocusing the electron beam to reduce local mechanical stress, minimize vibration, and prevent fiber damage during deposition, thereby enabling the one-step growth of platinum nanopillars with sub 20 nm spatial precision and high structural fidelity directly on suspended TNFs. The fabricated structures were characterized using SEM, EDX, and their optical properties were investigated through broadband scattering spectra and polarization resolved measurements, showing strong agreement with Finite Difference Time Domain (FDTD) simulations. Numerical modeling further reveals that ordered arrays of nanopillars can shape and direct the scattered field along the fiber axis, enabling directional emission. This work establishes BEBID as a versatile bottom up nanofabrication approach for functional photonic architectures on fragile substrates, with direct applications in quantum photonics, nano optics, and on fiber plasmonic sensing.