Ytterbium Rydberg NQO

From few- to many-body physics with Yb Rydberg polaritons

Strong interaction and the resulting blockade mechanism offered by Rydberg atoms are key to generate strong and long-range atom-photon and photon-photon interaction. The YQO project primarily aims to implement Rydberg-mediated photon-photon interaction by utilizing ultra-cold Yb Rydberg atoms.
This novel species in the context of Rydberg quantum optics provides multiple advantages that enable the realization of large interacting Rydberg polariton systems. Main goal of the project is to study few- to many-body open systems of interacting photons.Few to many body physics with polaritons.

Yb atoms have two valence electrons like alkaline-earth metals and helium. In such 2e systems, narrow intercombination lines associated with spin-flipping singlet-triplet transitions offer many new possibilities compared to single-valence electron atoms like the alkalis. Among these new options are novel schemes to produce dense, ultra-cold atomic ensembles solely through laser-cooling and metastable excited states, which can function as long-lived states in novel excitation schemes.

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The main goal of the ytterbium project is to study few- to many-body open systems of interacting photons.

Laser cooling and trapping of Yb

Main chamber - design

A rendering of the experimenta setup

Main chamber - how it looks in reality

The first iteration of the experimental design.

Electric field control plates

The electric field control for providing a stable environment for Rydberg atoms.

Our Yb apparatus combines a short loading cycle for large samples of laser-cooled Yb with single-photon Rydberg excitation and ion-detection in a separate science chamber. Starting with a dispenser-loaded 2D-MOT, Yb atoms are transferred into a two-color 3D shell MOT and finally into a highly elongated optical trap. The chamber design provides high-NA access to the trapping region from all three directions, enabling few-photon EIT on one axis and high-resolution imaging and trap structuring on the other two. In-vacuum electrodes are used for electric field cancellation as well as field-ionization of individual Rydberg atoms. The produced Yb ions are detected on a multi-channel plate.

YQO energy level

Ytterbium level scheme showing relevant energy levels for trapping and cooling.

Blue MOT

Fluorescence of laser cooled ytterbium atoms. The atoms are cooled and trapped with 399 nm laser light.

Green MOT

The fluorescence of the ytterbium atoms depends on what lasers are used for the cooling and trapping. Here the atoms are addressed with 556 nm light.

Rydberg EIT setup

In the context of Rydberg-mediated photon interactions, we utilize the broad singlet transitions to implement a ladder scheme for electromagnetically-induced transparency (EIT). In Yb, the two transition wavelengths associated with the probe (399nm) and control (395nm) lasers are very close in wavelength. This results in the suppression of motional dephasing and hence increased coherence time for stored or slowly propagating photons. Furthermore, the choice of short probe wavelength can be utilized for an extended overlap in a free space setting, resulting in a longer optical medium.

Probe and control setup

Schematic of probe control setup with options for counter or co-propagating beams.

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