%0 Journal Article
%A Bode, Tim
%A Kajan, Michael
%A Meirinhos, Francisco
%A Kroha, Johann
%T Non-Markovian dynamics of open quantum systems via auxiliary particles with exact operator constraint
%J Physical review research
%V 6
%N 1
%@ 2643-1564
%C College Park, MD
%I APS
%M FZJ-2024-01810
%P 013220
%D 2024
%X We introduce an auxiliary-particle field theory to treat the non-Markovian dynamics of driven-dissipative quantum systems of the Jaynes-Cummings type. It assigns an individual quantum field to each reservoir state and provides an analytic, faithful representation of the coupled system-bath dynamics. We apply the method to a driven-dissipative photon Bose-Einstein condensate (BEC) coupled to a reservoir of dye molecules with electronic and vibronic excitations. The complete phase diagram of this system exhibits a hidden, non-Hermitian phase transition separating temporally oscillating from biexponentially decaying photon density correlations within the BEC. On one hand, this provides a qualitative distinction of the thermal photon BEC from a laser. On the other hand, it shows that one may continuously tune from the BEC to the lasing phase by circumventing a critical point. This auxiliary-particle method is generally applicable to the dynamics of open, non-Markovian quantum systems.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:001187633700003
%R 10.1103/PhysRevResearch.6.013220
%U https://juser.fz-juelich.de/record/1023797