Bi-polarons in atomic Bose-Einstein condensates

New paper in PRL: Bi-polarons are bound states of two quasiparticles that exchange sound modes.

2018.07.12 | Ole J. Knudsen

The green balls illustrate two polarons, which bind forming a bipolaron

They have intrigued physicists for decades giving rise to important many-body phenomena such as electrical conduction in polymers, organic magnetoresistance, and perhaps even high temperature superconductivity. In a new paper published in Physical Review Letters in July 2018 (, A. Camacho-Guardian, L. A. Peña Ardila, T. Pohl, and G. M. Bruun, all from IFA, show that bipolarons exist in atomic Bose-Einstein condensates (BECs) under quite general conditions. To do so, the authors develop an effective low energy theory, which is shown to be accurate even for strong interactions by comparing to numerical Monte-Carlo calculations. Such accurate theories for strongly interacting many-body systems are rare.

The result paves the way for using the powerful new quantum technologies developed for atomic gases to explore bipolarons with unprecedented accuracy and in regimes never realized before. Indeed, the first observation worldwide of a polaron in a BEC was achieved by J. Arlts group here at IFA, and given this new result, the hunt is now on for first detection of the bipolaron in close collaboration with A. Camacho-Guardian and co.!

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