arXiv subjects

Giovanni Cichelli

Publications and source records attributed to Giovanni Cichelli.

3 recordsLinked to original sources

arXiv2026

Free-space multipass optical parametric amplifier

Scaling the efficiency of optical parametric amplifiers (OPAs) without degrading spatio-temporal pulse quality is fundamentally limited by spatio-temporal walk-off, intensity dependent gain, and back-conversion. Here, we numerically and experimentally demonstrate an OPA architecture based on a free-propagating quasi-periodic geometry that overcomes these bottlenecks. Operating within a single nonlinear crystal, the system utilizes pass-by-pass dichroic idler rejection to suppress back-conversion, a birefringent crystal for temporal resynchronization, and free-space diffraction to improve the spatial overlap along propagation. Starting from 1.9 {\mu}J 330 fs pulses at 515 nm and a continuous-wave seed at 783 nm, the generation of 0.8 {\mu}J 160 fs signal pulses at the same wave-length is obtained at a repetition rate of 500 kHz. This simple architecture achieves a 64% quantum efficiency, a 42% pump-to-signal conversion efficiency, and 80 dB of gain while maintaining excellent spatial and temporal quality, providing a scalable platform for ultrafast sources with arbitrary emission wavelengths

physics.optics↗

arXiv2026

Observation of intrastate and interstate facilitation between Rydberg S, P and D levels

We report experimental results on Rydberg facilitation, whereby Rydberg levels can be excited off-resonantly in the presence of a nearby Rydberg atom because of Rydberg-Rydberg interactions, for high-lying $S$, $P$ and $D$ levels in rubidium. Facilitation is detected both through an enhancement of the number of excited atoms for off-resonant excitation (either blue or red detuning) and a positive Mandel $Q$ parameter indicating correlated excitation events (super-Poissonian counting statistics). We also calculate the pair-state potentials for the Rydberg states involved and find that our experimental results agree with the expected facilitation conditions for repulsive potentials (blue detuning) and attractive potentials (red detuning), with $P$ and $D$ states exhibiting facilitation on both sides of the resonance. Finally, we investigate inter-state facilitation between two different Rydberg levels (70 $S$ and 70 $P$).

physics.atom-ph↗

arXiv2023

Controlled dissipation for Rydberg atom experiments

We demonstrate a simple technique for adding controlled dissipation to Rydberg atom experiments. In our experiments we excite cold rubidium atoms in a magneto-optical trap to $70$-S Rydberg states, whilst simultaneously inducing forced dissipation by resonantly coupling the Rydberg state to a hyperfine level of the short-lived $6$-P state. The resulting effective dissipation can be varied in strength and switched on and off during a single experimental cycle.

physics.atom-ph↗