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Quantum technologies

Dieter Meschede's research group

Quantum technologies with single neutral atoms


Cavity QED with single atoms


The goal of cavity quantum electrodynamics (cavity-QED) is to investigate and understand light-matter interaction at the most fundamental level by preparing a basic model system: a single atom strongly coupled to a single photon in a well-controlled environment. While individual atoms can be controlled well by laser-cooling and trapping techniques, photons have to be confined by reflecting them back and forth in cavities, which thus act as a "trap" for light.

In such a system the physics behind spontaneous and stimulated emission of light and the associated transitions of the atom between different quantum states can be investigated and illustrated in a unique way. This becomes possible due to the strong coupling between the atom and the cavity field, enabling a single atom to control the transmission of light through the cavity, and allowing a single photon to deterministically change the state of the atom. Quantum communication could be a future application of these controlled interaction between individual photons and atoms. 


Few-atom quantum systems

Fig. 1: The vacuum cell with lattice and imaging system: Individual cesium atoms can be trapped and observed.

Our team is working on quantum information processing using a small number of Cesium atoms. We load the atoms into a 1D optical lattice and use the spin of each atom as a quantum bit, with the ability to set and read out each atom individually—a quantum register. Our lattice uses a special wavelength which makes the optical potential state-depedent, giving us the ability to shift atoms in the lattice depending on their internal state. We are currently researching the phenomena exhibited by a single atom when it is coherently separated over several sites. Ultimately, our goal is the controlled interaction of two atoms, creating entanglement that can be used in a quantum computation.

Our recent results include:

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