Transient Density-Induced Dipolar Interactions in a Thin Vapor Cell

Abstract

We exploit the effect of light-induced atomic desorption (LIAD) to produce high atomic densities (n k 3 ) in a rubidium vapor cell. An intense off-resonant laser is pulsed for roughly one nanosecond on a micrometer-sized sapphire-coated cell, which results in the desorption of atomic clouds from both internal surfaces. We probe the transient (LIAD-induced) atomic density by time-resolved absorption spectroscopy. With a temporal resolution of ≈ 1 ns, we measure the broadening and line shift of the atomic resonances. This broadening and line shift is attributed to dipole-dipole interactions. As this timescale is much faster than the natural atomic lifetime, the experiment probes the dipolar interaction in a non-equilibrium situation beyond the usual steady-state, assumed in the derivation of the Lorentz-Lorenz shift. This fast switching of the atomic density and dipolar interactions could be the basis for future quantum devices based on the excitation blockade.

Purcell-enhanced dipolar interactions in nanostructures

“…Thermal atoms are therefore the most flexible nonlinear medium as far as scalability and integrability are concerned. So far, high-density cooperative effects were exclusively studied in thermal 2D systems, e.g., by probing atoms close to the surface via selective reflection spectroscopy [25,26] or in nanometer thin cells [27][28][29] where attractive interactions manifest themselves as a redshift and a broadening of the transmission spectrum consistent with the Lorentz-Lorenz scaling [30]. In this letter, we report the observation of Purcellenhanced cooperative effects in a 1D dense thermal rubidium vapor inside a deep sub-wavelength slot waveguide.…”

“…Benefitting from the miniaturized system, we have been able to achieve highly nonlinear behaviour with an estimated number of 45 photons required for a phase shift of π out of which ≈ 8% are absorbed on resonance. Exclusive to our scalable and integrated platform we can use in future the effect of light induced atomic desorption in order to switch the density by 2 orders of magnitude within a nanosecond timescale [29]. Via coupling to the guided mode it is also possible to increase the effective optical depth without changing the actual density of emitters [40] useful for memory applications [41].…”