TY - JOUR A1 - Palm, Timo A1 - Nalbach, Peter T1 - Quasi-adiabatic path integral approach for quantum systems under the influence of multiple non-commuting fluctuations T2 - The journal of chemical physics - bridges a gap between journals of physics and journals of chemistry N2 - Quantum systems are typically subject to various environmental noise sources. Treating these environmental disturbances with a system-bath approach beyond weak coupling, one must refer to numerical methods as, for example, the numerically exact quasi-adiabatic path integral approach. This approach, however, cannot treat baths which couple to the system via operators, which do not commute. We extend the quasi-adiabatic path integral approach by determining the time discrete influence functional for such non-commuting fluctuations and by modifying the propagation scheme accordingly. We test the extended quasi-adiabatic path integral approach by determining the time evolution of a quantum two-level system coupled to two independent baths via non-commuting operators. We show that the convergent results can be obtained and agreement with the analytical weak coupling results is achieved in the respective limits. Y1 - 2018 UR - https://whge.opus.hbz-nrw.de/frontdoor/index/index/docId/3130 SN - 1089-7690 VL - 149 IS - 21 SP - 214103 ER -