Direct loading of optical traps using hollow-core photonic crystal fibers

Optical levitation of nano-particles provides novel approaches to cutting-edge sensors and tests of quantum physics at unprecedented mass scales. Today, experiments already operate in a regime (~ 1E-8 mBar) where decoherence from photonic recoil due to the optical trap starts to dominate over gas scattering [1] and where the quantization of the energy spectrum becomes relevant [2,3].
Foundational experiments still need to surpass this and use free-fall experiments that will require still lower pressures. However, current methods to load particles into optical traps make this challenging. Here, we present our progress towards a solution: an optical conveyor belt inside a hollow-core photonic crystal fiber [2] and particle handover to an optical tweezer. We transport particles from a loading chamber at low vacuum, transferring them directly to an optical tweezer, focused to below 1 micron, that switches on at particle arrival. Only a few centimeters of HCPCF can bridge the pressure difference from the loading chamber (1mbar) to the science chamber (1E-10 mbar).

[1] V. Jain, et al., PRL 116, 243601 (2016).
[2] U. Delić, et al., Science 367, 892-895 (2020)
[3] Tebbenjohanns et al., PRL 124, 013603 (2020)
[4] D. Grass, et al., APL 108, 221103 (2016).