Saturated tabletop lasers operating at $5\mathrm{Hz}$ repetition rate with average powers $>1\mu \mathrm{W}$ were demonstrated at wavelengths between 16.5 and $13.9\mathrm{nm}$ in the $4d{}^{1}S_0–4p{}^{1}P_1$ transitions of Ni-like ions. The results were obtained using picosecond laser heating pulses with an energy of only $1\mathrm{J}$ by optimizing the angle of incidence for maximum energy deposition. Lasing was also observed for shorter wavelength transitions of the same isoelectronic sequence, with amplification in the $11.9\mathrm{nm}$ line of Ni-like Sn approaching gain saturation, and progressively reduced gain for wavelengths as low as $10.9\mathrm{nm}$ for Ni-like Te. These high repetition rate soft x-ray lasers will enable new applications in science and the development of unique metrology and processing tools for industry.

We report saturated operation of an 18.9-nm laser at 5-Hz repetition rate. An amplification with a gain–length product GL of 15.5 is obtained in the $4d {{}^{1}S}_0–4p {{}^{1}P}_1$ laser line of Ni-like Mo in plasmas heated at grazing incidence with $\sim 1‐\mathrm{J}$ pulses of 8.1-ps duration from a tabletop laser system. Lasing is obtained over a broad range of time delays and pumping conditions. We also measure a GL of 13.5 in the 22.6-nm transition of the same ion. The results are of interest for numerous applications requiring high-repetition-rate lasers at wavelengths below 20 nm.

We demonstrate the generation of an intense soft-x-ray-laser beam by saturated amplification of high harmonic seed pulses in a dense transient collisional soft-x-ray-laser plasma amplifier created by heating a titanium target. Amplification in the 32.6 nm line of Ne-like Ti generates laser pulses of subpicosecond duration that are measured to approach full spatial coherence. The peak spectral brightness is estimated to be $\sim 2\times {10}^{26}\mathrm{\text{photons}}/(\mathrm{s}{\mathrm{mm}}^2{\mathrm{mrad}}^{2}0.01\%\mathrm{\text{bandwidth}})$. The scheme is scalable to produce extremely bright lasers at very short wavelengths with full temporal and spatial coherence.

We have acquired images with a spatial resolution better than $38\mathrm{nm}$ by using a tabletop microscope that combines $13\mathrm{nm}$ wavelength light from a high-brightness tabletop laser and Fresnel zone plate optics. These results open a gateway to the development of compact and widely available extreme-ultraviolet imaging tools capable of inspecting samples in a variety of environments with a $15–20\mathrm{nm}$ spatial resolution and a picosecond time resolution.

We report experimental results on the action of selected local environments on the fidelity of the quantum teleportation protocol, taking into account nonideal, realistic entangled resources. Different working conditions are theoretically identified, where a noisy protocol can be made almost insensitive to the further addition of noise. We put to test these conditions on a photonic implementation of the quantum teleportation algorithm, where two polarization entangled qubits act as the entangled resource and a path qubit on Alice encodes the state to be teleported. Bob's path qubit is used to implement a local environment, while the environment on Alice's qubit is simulated as a weighted average of different pure states. We obtain a good agreement with the theoretical predictions, experimentally recreate the conditions to obtain a noise-induced enhancement of the protocol fidelity, and identify parameter regions of increased insensibility to interactions with specific noisy environments.

We report gain-saturated operation of a $13.2\mathrm{nm}$ tabletop laser in Ni-like Cd at a $5\mathrm{Hz}$ repetition rate. A gain–length product $G\times L=17.6$ was obtained by heating a precreated plasma with $8\mathrm{ps}$ duration Ti:sapphire laser pulses with an energy of only $1\mathrm{J}$ impinging at a grazing angle of 23°. With an average power of $\sim 1\mu \text{W}$, this laser is an attractive coherent source for at-wavelength metrology of extreme UV lithography optics and other applications.