Laser-cooled atoms inside a hollow-core photonic-crystal fiber

Abstract

We describe the loading of laser-cooled rubidium atoms into a single-mode hollow-core photoniccrystal fiber. Inside the fiber, the atoms are confined by a far-detuned optical trap and probed by a weak resonant beam. We describe different loading methods and compare their trade-offs in terms of implementation complexity and atom-loading efficiency. The most efficient procedure results in loading of ∼30,000 rubidium atoms, which creates a medium with optical depth ∼180 inside the fiber. Compared to our earlier study [1] this represents a six-fold increase in maximum achieved optical depth in this system.

Optimized coupling of cold atoms into a fiber using a blue-detuned hollow-beam funnel

“…Table I shows that we obtained excellent agreement with the experimental data. We also applied our model against the cold atom coupling experiment reported recently by Bajcsy et al [25] (summarized in Sec. I).…”

“…Soon after, they improved the atom coupling efficiency by a factor of 6 using a collimated hollow-beam and a repulsive sheet beam. The system effectively acts as an "optical elevator" that lowers the MOT within 1 mm of the fiber input [25]. When the sheet beam is turned off, gravity and a red-detuned Gaussian beam funnels the atoms into the core.…”

Coherent-state-induced transparency

“…(12) for classical control field of the same intensity Ω 2 c = g 2 2 α|Î 2 |α = g 2 2 |α| 2 . We consider the configuration of transversely trapped atoms inside the HC-PCF, which has been experimentally realized in [11,12]. The atoms are confined in the radial direction with a radius smaller than the radius of the fiber core.…”

“…Since its first experimental observation in strontium vapors [2], it has been thoroughly investigated in different material systems including quantum dots [3], quantum wells [4], nanoplasmonics [5], metamaterials [6], and optomechanical systems [7]. Many applications of EIT, ranging from reversible mapping of light-matter states in quantum memory [8][9][10] to all-optical switching of one beam by another [11][12][13] and cross-coupling nonlinearities at the few-photon level [14,15], reveal its ability as a basic tool for implementation of quantum information processing. However, to date, only classical fields are employed in usual EIT schemes to yield transparency in probe light absorption, while, despite the fundamental importance, the transparency induced in atomic ensembles by quantum fields has not been explored yet, except for the cavity-based EIT, where the classical control beam is replaced by a cavity vacuum field [16].…”

“…This behavior results from the modification of the photon statistics in the coherent state, where the increase of mode number shifts the * Electronic address: agogyan@gmail.com maximum of photon distribution to the Fock states with small number of photons provided that the total intensity of the control field remains unchanged. To enhance the atom-photon interaction and cancel the Doppler broadening, we consider propagation of a weak probe pulse in a cold atomic ensemble, such as the atoms inside a hollow-core photonic crystal fiber (HC-PCF) of a few microns in diameter, which can tightly confine both atoms and photons transversely over long interaction lengths [11,12,[17][18][19][20][21]. Of course, different dissipative effects are significant for coherent states with different mode numbers, however, we ignore these complications to concentrate on more fundamental issues.…”