Ultracold atoms permit direct observation of quasiparticle dynamics

Recommendable! Amazing stuff! Some fascinating research coming out of Aarhus, Denmark! These quasiparticles, besides e.g. gravity, may also pose a challenge to the Standard Model (just blogged here about it).

"Theories of how quasiparticles form have been around for more than 80 years, but direct observations of the process have remained elusive due to experimental challenges. ...
Due to the high densities and fast timescales of this system, however, experiments cannot directly probe such quasiparticle behaviour in solids. The Aarhus team instead studied an analogue system: a quasiparticle called a polaron in a Bose-Einstein condensate (BEC). This dilute gas of ultracold atoms offers a pristine, controlled environment in which to study the quantum dynamics of many-body phenomena. ...
“Quasiparticles are exceedingly interesting to study since they may be composed by numerous particles and their excitations,” ... “The Bose polaron is an excellent example of such a challenging quasiparticle that nonetheless holds great potential for helping us to understand exotic technologies like organic semiconductors and superconductors. ..."

"... These results offer a systematic picture of polaron formation from weak to strong impurity interactions. They reveal three distinct regimes of evolution with dynamical transitions that provide a link between few-body processes and many-body dynamics. Our measurements reveal universal dynamical behaviour in interacting many-body systems and demonstrate new pathways to study non-equilibrium quantum phenomena."

Ultracold atoms permit direct observation of quasiparticle dynamics – Physics World

Here is the link to the underlying research paper:

Non-equilibrium quantum dynamics and formation of the Bose polaron