PHYSICAL REVIEW A 90
, 062104 (2014)
ISSN: 1050-2947, SCI
Non-Markovianity of a two-level system transversally coupled to multiple bosonic reservoirs
Zhong-Xiao Man, Nguyen Ba An and Yun-Jie Xia
Dynamics of a two-level open system transversally coupled to a single zero-temperature bosonic reservoir
may be Markovian or non-Markovian, depending on whether the system-reservoir coupling is weak or strong.
In this paper, we show that when the system is simultaneously coupled to N reservoirs its dynamics is always
non-Markovian, provided that N >= Ncr, with Ncr a critical number depending on the reservoirs’ parameters.
Quantitatively, the non-Markovianity N is shown proportional to the number of contributed reservoirs. We
explain our results in terms of the pseudomode theory, finding out that when N >= Ncr the pseudomodes of all
the reservoirs can always partially return information back to the system, no matter how strong the couplings
between the system and each individual reservoir.