Observing the Birth of Quasiparticles in Real Time

October 6, 2016

Fig. 1 Illustration of the experimental setup and procedure.*
[Reprinted with permission from AAAS ©2016]

The nonequilibrium dynamics of many-body quantum systems are tricky to study experimentally or theoretically. As an experimental setting, dilute atomic gases offer an advantage over electrons in metals. In this environment, the heavier atoms make collective processes that involve the entire Fermi sea occur at the sluggish time scale of microseconds. An international team of theoretical physicists, including Prof. Eugene Demler, studied these dynamics by using a small cloud of 40K atoms that was positioned at the center of a far larger 6Li cloud. Controlling the interactions between K and Li atoms enabled a detailed look into the formation of quasiparticles associated with K "impurity" atoms.

* Read the original article: M. Cetina, M. Jag, R.S. Lous, I. Fritsche, J.T.M. Walraven, R. Grimm, J. Levinsen, M.M. Parish, R. Schmidt, M. Knap, and E. Demler, "Ultrafast many-body interferometry of impurities coupled to a Fermi sea," Science 354:6308 (07 Oct 2016) DOI: 10.1126/science.aaf5134. Also read "Observing the birth of quasiparticles in real time" on phys.org.