Enhanced cold-atom quantum memories by dynamic density engineering

The proposal aims to improve the performance of a QM system that is based on Bose-Einstein condensates (BEC). BECs are a special phase of matter, where all the atoms that make up the cloud occupy the same quantum wavefunction due to the extremely low temperatures. Despite this low operating temperature, atom-atom collisions result in information loss and therefore limit the achievable maximum storage time. We have recently demonstrated a way to mitigate this problem: by operating the experiment in microgravity, the BEC cloud is allowed to expand after the storage, which will reduce atom-atom collision rates. After a certain time, the cloud is “refocused” and the stored information can be read out efficiently.

In this proposal, we lay out a concrete roadmap to experimentally realize this scheme in ground-based experiments. The project has several steps: we will start with storing non-classical states in a BEC QM, which has not been performed before. Afterwards, by carefully expanding the BEC with the help of laser beams, we will explore and quantify density-dependent effects on the stored information. Finally, we will perform a free-fall experiment by dropping the BEC cloud from a few centimeters in our experimental setup. This technique may find applications in the rapidly developing field of space-based quantum information science.deep