arXiv subjects

Neven Šantić

Publications and source records attributed to Neven Šantić.

4 recordsLinked to original sources

arXiv2026

Observation of Discrete 1D Solitons in an Optically Induced Lattice in Rubidium Atomic Vapor

The manipulation of light in periodic structures is fundamental to the development of discrete photonics and provides a versatile platform for controlling light propagation in integrated and quantum photonic systems. This work reports the experimental observation of discrete one-dimensional (1D) solitons in a photonic lattice, optically induced in warm rubidium vapor. The lattice is generated by the interference of two coupling laser fields intersecting at a small angle, which creates a spatially modulated 1D refractive index. When a probe beam is focused into a single lattice site, discrete diffraction is observed. By increasing the probe intensity, discrete solitons emerge as a result of the balance between discrete diffraction and self-focusing within the nonlinear atomic medium. Experimental results are supported by numerical simulations, in which the refractive index is modeled via optical Bloch equations for a multilevel atomic system driven by the coupling and probe fields in a $Λ$ configuration. These results, combined with the inherent controllability of gain and loss in atomic vapors, suggest that this platform provides a versatile foundation for exploring non-Hermitian nonlinear dynamics in photonic lattices.

physics.optics↗

arXiv2026

Collective light shifts of many longitudinal cavity modes induced by coupling to a cold-atom ensemble

We experimentally study the interaction between a cold atom cloud and many longitudinal modes of a high quality Fabry-Perot cavity, by measuring signatures of collective light shifts in the cavity transmission spectrum of an optical frequency comb probe. Using a resonator coupled to more than $10^5$ intracavity atoms, we detect significant shifts of $\sim 100$ cavity modes simultaneously, which is a direct manifestation of physics beyond the hitherto explored regime of cavity-cold atom interaction with only single or few longitudinal modes at a time. For the cavity mode closest to the atomic resonance, we demonstrate a bistability in the transmission spectrum, arising due to a combined coupling of the cloud to an external pump laser and a cavity mode probed by the optical frequency comb. These results provide a first step toward deeper exploration of multifrequency cavity quantum electrodynamics, where ultrashort pulsed sources could be used for optical manipulation, cooling and entanglement of cold atoms in a resonator.

quant-ph↗

arXiv2025

Lifetime measurement of the 5s5p 1P1 state in strontium

We present a direct lifetime measurement of the $5s5p~^1P_1$ state of strontium using time-correlated single-photon counting of laser induced fluorescence in a hot atomic beam. To achieve fast switch-off times and a high signal-to-noise ratio, we excite the strontium atoms with a femtosecond pulsed laser at $\approx$461 nm and collect the fluorescence onto a hybrid single-photon detector. Analysis of the measured exponential decay gives a lifetime of the $^1P_1$ state of $τ= (5.216 \pm 0.006_{stat} \pm 0.013_{sys})$ ns, where all the systematic effects have been thoroughly considered.

physics.atom-ph↗

arXiv2024

Absolute frequency measurement of the 5s5p $^1P_1$ - 5s5d $^1D_2$ transition in strontium

We report on the absolute frequency determination of the 5s5p $^1P_1$ - 5s5d $^1D_2$ transition in atomic strontium, achieved through frequency comb-referenced laser-induced-fluorescence (LIF) spectroscopy. We excite the 5s$^2$ $^1S_0$ - 5s5p $^1P_1$ transition using an on-resonance laser at $\approx$461 nm, and then measure the variation in the LIF signal while scanning the laser at $\approx$767 nm across the 5s5p $^1P_1$ - 5s5d $^1D_2$ transition. We determine the absolute frequency of $390599571.7\pm0.4$ MHz, with an accuracy that surpasses the previous most accurate measurement by two orders of magnitude. This measurement technique can be readily applied for precision spectroscopy of high-lying states not only in strontium, but also in other atomic species.

physics.atom-ph↗