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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.

DOI: 10.1103/PhysRevA.90.062104