Physicists control transport of stored light

For the experiment, atoms of rubidium-87 are first pre-cooled and then transported to the main test area, which is a custom-made vacuum chamber. There they are cooled to temperatures of just a few microkelvins. Credit: Windpassinger group

A team of physicists led by Professor Patrick Windpassinger at Johannes Gutenberg University Mainz (JGU) has successfully transported light stored in a quantum memory over a distance of 1.2 millimeters.

They have demonstrated that the controlled transport process and its dynamics has only little impact on the properties of the stored light. The researchers used ultra-cold rubidium-87 atoms as a storage medium for the light as to achieve a high level of storage efficiency and a long lifetime.

The controlled manipulation and storage of quantum information as well as the ability to retrieve it are essential prerequisites for achieving advances in quantum communication and for performing corresponding computer operations in the quantum world. Optical quantum memories, which allow for the storage and on-demand retrieval of quantum information carried by light, are essential for scalable quantum communication networks. For instance, they can represent important building blocks of quantum repeaters or tools in linear quantum computing. In recent years, ensembles of atoms have proven to be media well suited for storing and retrieving optical quantum information. Using a technique known as electromagnetically induced transparency (EIT), incident light pulses can be trapped and coherently mapped to create a collective excitation of the storage atoms. Since the process is largely reversible, the light can then be retrieved again with high efficiency. (

The paper has been published in Physical Review Letters.

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