Raman gas self-organizing into deep nano-trap lattice.

M Alharbi,A Husakou,B Debord,M Chafer,F Gérôme,F Benabid

doi:10.1038/ncomms12779

Abstract

Trapping or cooling molecules has rallied a long-standing effort for its impact in exploring new frontiers in physics and in finding new phase of matter for quantum technologies. Here we demonstrate a system for light-trapping molecules and stimulated Raman scattering based on optically self-nanostructured molecular hydrogen in hollow-core photonic crystal fibre. A lattice is formed by a periodic and ultra-deep potential caused by a spatially modulated Raman saturation, where Raman-active molecules are strongly localized in a one-dimensional array of nanometre-wide sections. Only these trapped molecules participate in stimulated Raman scattering, generating high-power forward and backward Stokes continuous-wave laser radiation in the Lamb–Dicke regime with sub-Doppler emission spectrum. The spectrum exhibits a central line with a sub-recoil linewidth as low as ∼14 kHz, more than five orders of magnitude narrower than conventional-Raman pressure-broadened linewidth, and sidebands comprising Mollow triplet, motional sidebands and four-wave mixing.

Highlights

Trapping or cooling molecules has rallied a long-standing effort for its impact in exploring new frontiers in physics and in finding new phase of matter for quantum technologies
A 20 m long home-made photonic bandgap guiding hollow-core photonic crystal fibre (HC-PCF), filled with molecular hydrogen[19] at uniform pressure in the range of 20–50 bar, is pumped with a randomly polarized 1,061 nm wavelength Yb-fibre continuous-wave (CW) laser. In such a system stimulated Raman scattering (SRS) occurs, where the incoming input laser photons transform into lower-energy Stokes photons by transferring their energy difference to molecular rotational and/or vibrational transitions
The strong localization of the molecules raises the question on the possibility of collective effects such as superradiance, or on the diffusion dynamics in this regime and its effect on the linewidth narrowing limit

Summary

Introduction

Trapping or cooling molecules has rallied a long-standing effort for its impact in exploring new frontiers in physics and in finding new phase of matter for quantum technologies. The molecules create their own optical lattice by generating via stimulated Raman scattering (SRS) forward and backward Stokes waves from quantum noise and to form a standing wave along a section of the fibre.

Results

Conclusion