Giant Rydberg Atoms Confined in a Micro-glass Cell
Rydberg atoms are highly sensitive atoms, as one electron is only loosely bound. Compared to “normal“ atoms, which are one tenth of a nanometer in size those giant atoms are ~100 nanometers large. Due to their sensitivity, they are very useful for quantum logic operations. As they can feel each other over distances up to several micrometers, they can be used as conditional switches for quantum states, for example to connect nodes of a quantum network.
The miniaturization of such quantum devices will seemingly also be hindered by this large sensitivity, as Rydberg atoms also were expected to interact strongly with confining walls. Now, researchers of the 5. Physikalisches Institut at the Universität Stuttgart showed contrary to that expectation that it is possible to confine giant Rydberg atoms in microscopic glass cells under circumstances without significant disturbance. For this, micron-sized glass cells were filled with “normal” hot atoms in the vapor phase. Then they were converted into Rydberg atoms by laser excitation.
They report on the progress appears in Nature Photonics. It seems that hot Rydberg atoms confined in micro-glass cells have become hot candidates for miniaturized quantum devices at or even above room temperature.
Researchers from the 5. Physikalisches Institut have been working with those giant atoms for several years now. Up to now, their research concentrated on ultracold atoms. Using elaborate cooling techniques in big UHV chambers, the atoms could be isolated from the environment. They recently have investigated the interaction between Rydberg atoms and have observed a novel molecular bond based on Rydberg electrons.
The apparatus for the experiments is, however, quite complex and not well-suited for applications. Therefore, they were looking for an easy-to-handle alternative that is scalable and suited for massively parallel production.
Microstruturing of glass is a well-established technique and also is applied in flat-panel display technology. In order to use this technology for the confinement of atoms, it was necessary to investigate the interaction of Rydberg atoms with nearby glass walls. If the sensitive Rydberg atoms would be disturbed by the wall, then applications like quantum information processing would become impossible.
Now, the group at the 5. Physikalisches Institut of the Universität Stuttgart has succeeded in investigating the interaction of Rydberg atoms with glass walls. They confined them between two glass walls separated by less than 1 micrometer and detected the energy shifts using a coherent spectroscopy technique which is very sensitive to loss of quantum information (decoherence). They found that different Rydberg states interact with the wall with different strengths and found a specific state that was almost not affected by the wall. Therefore, it now seems feasible to apply Rydbergatoms in micro-cells for quantum information purposes.