A collaboration between the theoretical group of Georg Bruun and two experimental groups of Michael Drewsen (ion traps) and Jan Arlt (ultracold atomic gases) in the Center for Complex Quantum Systems (CCQ) at IFA proposes a promising method to explore the mediated interaction between two ions in quantum degenerate gases.

Mediated interactions play a crucial role for our understanding of nature as well as for technological applications. However, one has so far not been able to explore mediated interactions in a systematic way using quantum simulation. In recent years, hybrid atom-ion systems have emerged as a powerful new quantum simulation platform. Their strength is that they combine the exquisite control and detection methods of individual ions with the great flexibility of atomic gases. Inspired by the tremendous progress in realizing hybrid atom-ion systems, we explored the mediated interaction between two trapped ions in quantum degenerate Bose and Fermi gas. We obtain its analytical expression at large distance and find that the mediated interaction can be a significant addition to the bare Coulomb interaction between the ions, when an atom-ion bound state is close to threshold. Furthermore, we show that the interaction between two ions mediated by a surrounding Bose-Einstein condensate leads to observable frequency shifts of the ion phonon modes. The results are possible to be validated with the effort of the two experimental groups (Michael Drewsen and Jan Arlt) of our center in the future. 

Read the article here: 10.1103/PhysRevLett.129.153401