The flexible delivery of single-frequency lasers is far more challenging than that of conventional lasers due to the onset of stimulated Brillouin scattering (SBS). Here we present the successful delivery of 100 W single-frequency laser power through 100 m of anti-resonant hollow-core fiber (AR-HCF) in an all-fiber configuration, with the absence of SBS. By employing a custom-designed AR-HCF with a mode-field diameter matching that of a large-mode-area panda fiber, the system achieves high coupling efficiency without the need for free-space components or fiber post-processing. The AR-HCF attains a transmission efficiency of 92%, delivering an output power of 100.3 W with a beam quality factor (M2) of 1.22. The absence of SBS is confirmed through monitoring backward light, which shows no increase in intensity. This all-fiber architecture ensures high stability, compactness and efficiency, potentially expanding the application scope of single-frequency lasers in high-precision metrology, optical communication, light detection and ranging systems, gravitational wave detection and other advanced applications.

Elemental abundances, particularly the C/O ratio, are seen as a way to connect the composition of planetary atmospheres with planet formation scenario and the disc chemical environment. We model the chemical composition of gas and ices in a self-gravitating disc on timescales of 0.5 Myr since its formation to study the evolution of C/O ratio due to dust dynamics and growth and phase transitions of the volatile species. We use the thin-disc hydrodynamic code FEOSAD, which includes disc self-gravity, thermal balance, dust evolution, and turbulent diffusion, and treats dust as a dynamically different and evolving component interacting with the gas. It also describes freeze-out, sublimation, and advection of four most abundant volatile species: H$_2$O, CO$_2$, CH$_4$, and CO. We demonstrate the effect of gas and dust substructures such as spirals and rings on the distribution of volatiles and C/O ratios, including the formation of multiple snowlines of one species, and point out the anticorrelation between dust-to-gas ratio and total C/O ratio emerging due to the contribution of oxygen-rich ice mantles. We identify time and spatial locations where two distinct trigger mechanisms for planet formation are operating and differentiate them by C/O ratio range: wide range of the C/O ratios of $0-1.4$ for streaming instability, and a much narrower range $0.3-0.6$ for gravitational instability (with the initial value of 0.34). This conclusion is corroborated by observations, showing that transiting exoplanets, which possibly experienced migration through a variety of disc conditions, have significantly larger spread of C/O in comparison with directly imaged exoplanets likely formed in gravitationally unstable outer disk regions. We show that the ice-phase $\textrm{C/O}\approx$0.2–0.3 between the CO, CO$_2$, and CH$_4$ snowlines corresponds to the composition of the Solar system comets, that represent primordial planetesimals.

Understanding the physics of electromagnetic pulse (EMP) emission and nozzle damage is critical for the long-term operation of laser experiments with gas targets, particularly at facilities looking to produce stable sources of radiation at high repetition rates. We present a theoretical model of plasma formation and electrostatic charging when high-power lasers are focused inside gases. The model can be used to estimate the amplitude of gigahertz EMPs produced by the laser and the extent of damage to the gas jet nozzle. Looking at a range of laser and target properties relevant to existing high-power laser systems, we find that EMP fields of tens to hundreds of kV/m can be generated several metres from the gas jet. Model predictions are compared with measurements of EMPs, plasma formation and nozzle damage from two experiments on the VEGA-3 laser and one experiment on the Vulcan Petawatt laser.

Quantum technologies (QT) are being awaited with excitement. They are supported by many governments, the corporate sector, international bodies and technology forecasters. There is discursive investment as well in terms of creating expectations and laying down a vision for the ‘Second Quantum Revolution’. Science and technology studies are also playing their part to think of the quantum future along with philosophical discussions around it. These visions and expectations perform an implicit and latent function of steering policy proposals and governance. At the current stage of development of quantum technologies, a comprehensive and cogent legal framework is hard to envisage. As it is difficult to foresee the final shape of these technologies, a way to proceed can be to focus on the legal enquiry related to economic, political and policy factors which contribute to its material emergence. This can broaden the focus from thinking about its impact to contextualizing its production and development. Further, it allows a way of determining the extent to which social science and ethical frames can apply to the governance of QT, given the legal and practical realities of technology production and use. This article maps the myriad governance frameworks being envisaged to think about the future of QT. It zooms onto the discussion related to the access divide being framed for QT to understand the points of legal intervention. It uses the case of quantum computing to understand the way legal and practical policy solutions have been ideated. It highlights the way these solutions entrench power of digital infrastructure providers further. This seeks to motivate further work to expand the scope of a legal framework for QT.

We examine the energy distribution of the fast radio burst (FRB) population using a well-defined sample of 63 FRBs from the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope, 28 of which are localised to a host galaxy. We apply the luminosity-volume ($V/V_{\mathrm{max}}$) test to examine the distribution of these transient sources, accounting for cosmological and instrumental effects, and determine the energy distribution for the sampled population over the redshift range $0.01 \lesssim z \lesssim 1.02$. We find the distribution between $10^{23}$ and $10^{26}$ J Hz$^{-1}$ to be consistent with both a pure power-law with differential slope $\gamma=-1.96 \pm 0.15$, and a Schechter function with $\gamma = -1.82 \pm 0.12$ and downturn energy $E_\mathrm{max} \sim 6.3 \, \times 10^{25}$ J Hz$^{-1}$. We identify systematic effects which currently limit our ability to probe the luminosity function outside this range and give a prescription for their treatment. Finally, we find that with the current dataset, we are unable to distinguish between the evolutionary and spectral models considered in this work.

We introduce a versatile high-repetition-rate solid tape target system suitable for relativistic laser-plasma driven secondary sources. We demonstrate the operation and stability monitoring based on a petawatt laser focused at 1 Hz. Experiments were carried out at the VEGA-3 laser system of the Centro de Láseres Pulsados facility where results for different tape materials and thicknesses are presented. Experimental proton spectra were recorded by a Thomson parabola spectrometer and a time-of-flight detector. In addition, non-invasive detectors, such as a target charging monitor and ionization chamber detectors, were tested as metrology for the stability of the source. Degradation of the proton signal at high-repetition-rate operation was observed and it was solved by online optimization of the relative focus position of the target and laser beam parameters. We report the use of the tape target for bursts of 1000 shots at 1 Hz with mean cut-off energies of about 10 MeV in optimized interaction conditions.

Fully relativistic particle-in-cell (PIC) simulations are crucial for advancing our knowledge of plasma physics. Modern supercomputers based on graphics processing units (GPUs) offer the potential to perform PIC simulations of unprecedented scale, but require robust and feature-rich codes that can fully leverage their computational resources. In this work, this demand is addressed by adding GPU acceleration to the PIC code Osiris. An overview of the algorithm, which features a CUDA extension to the underlying Fortran architecture, is given. Detailed performance benchmarks for thermal plasmas are presented, which demonstrate excellent weak scaling on NERSC's Perlmutter supercomputer and high levels of absolute performance. The robustness of the code to model a variety of physical systems is demonstrated via simulations of Weibel filamentation and laser-wakefield acceleration run with dynamic load balancing. Finally, measurements and analysis of energy consumption are provided that indicate that the GPU algorithm is up to ${\sim }$14 times faster and $\sim$7 times more energy efficient than the optimized CPU algorithm on a node-to-node basis. The described development addresses the PIC simulation community's computational demands both by contributing a robust and performant GPU-accelerated PIC code and by providing insight into efficient use of GPU hardware.

We present results of frequency tripling experiments performed at the Hilase facility on a cryogenically gas cooled multi-slab ytterbium-doped yttrium aluminum garnet laser system, Bivoj/DiPOLE. The laser produces high-energy ns pulses at 10 Hz repetition rate, which are frequency doubled using a type-I phase-matched lithium triborate (LBO) crystal and consequently frequency summed using a type-II phase-matched LBO crystal. We demonstrated a stable frequency conversion to 343 nm at 50 J energy and 10 Hz repetition rate with conversion efficiency of 53%.

We construct a mean-field model that describes the nonlinear dynamics of a spin-polarized electron gas interacting with fixed, positively charged ions possessing a magnetic moment that evolves in time. The mobile electrons are modelled by a four-component distribution function in the two-dimensional phase space $(x,v)$, obeying a Vlasov–Poisson set of equations. The ions are modelled by a Landau–Lifshitz equation for their spin density, which contains ion–ion and electron–ion magnetic exchange terms. We perform a linear response study of the coupled Vlasov–Poisson–Landau–Lifshitz (VPLL) equations for the case of a Maxwell–Boltzmann equilibrium, focussing in particular on the spin dispersion relation. Conditions of stability or instability for the spin modes are identified, which depend essentially on the electron spin polarization rate $\eta$ and the electron–ion magnetic coupling constant $K$. We also develop an Eulerian grid-based computational code for the fully nonlinear VPLL equations, based on the geometric Hamiltonian method first developed by Crouseilles et al. (J. Plasma Phys., vol. 89, no. 2, 2023, p. 905890215). This technique allows us to achieve great accuracy for the conserved quantities, such as the modulus of the ion spin vector and the total energy. Numerical tests in the linear regime are in accordance with the estimations of the linear response theory. For two-stream equilibria, we study the interplay of instabilities occurring in both the charge and the spin sectors. The set of parameters used in the simulations, with densities close to those of solids (${\approx }10^{29}\ {\rm m}^{-3}$) and temperatures of the order of 10 eV, may be relevant to the warm dense matter regime appearing in some inertial fusion experiments.

We investigate the global stability properties of an electron–positron pair plasma in the linear regime. The plasma is confined by the magnetic field of an infinitely long wire. This configuration is the large-aspect-ratio limit of the levitated dipole experiment of the APEX collaboration. The stability is governed by the diocotron mode and the interchange mode. The diocotron mode dominates in the case of a cold, non-neutral plasma. For specific density profiles we find analytic solutions. We derive a necessary condition for instability and find unstable solutions if the plasma forms a thin shell around the wire. Solutions for arbitrary density profiles with finite temperature are obtained numerically. We find that finite-temperature effects stabilise the diocotron mode. The interchange mode, on the other hand, dominates if the plasma is neutral and has a finite temperature. This mode becomes unstable for a steep-enough density gradient, that is aligned with the gradient of the magnetic field strength and is stabilised by the equilibrium $E\times B$ drift of a non-neutral plasma.

Nonlinear compression experiments based on multiple solid thin plates are conducted in an ultra-high peak power Ti:sapphire laser system. The incident laser pulse, with an energy of 80 mJ and a pulse width of 30.2 fs, is compressed to 10.1 fs by a thin-plate based nonlinear compression. Significant small-scale self-focusing is observed as ring structures appear in the near-field of the output pulse at high energy. Numerical simulations based on the experimental setup provide a good explanation for the observed phenomena, offering quantitative predictions of the spectrum, pulse width, dispersion and near- and far-field distributions of the compressed laser pulse.

Laser systems based on coherent beam combination (CBC) that rely on tiled pupil architecture intrinsically carry digital capabilities independently applicable to all three essential characteristics of a laser pulse: amplitude, phase and polarization. Those capabilities allow the far-field energy distribution to be flexibly tailored in real time. Operation in the femtosecond regime at high repetition rates gives access to a wide range of applications requiring both high peak and average powers. We address the task of independent peak versus average power adjustment needed for applications seeking to decouple nonlinear phenomena associated with GW peak power from the thermal load inherent to kW average power operation. The technical solutions proposed are presented in the framework of the Ecole Polytechnique XCAN CBC laser platform (61 independent channels) with an emphasis on thermal management measures implemented to ensure its nominal operation.