Systematic non-perturbative approach to quantum non-Markovian dynamics

Last updated March 29, 2019 by Alessandro Ferraro

Wednesday, March 27th 2019, 04:00 PM, MAPTC/0G/006

Speaker: A. Smirne (Ulm University).

I will present a general nonperturbative approach to non-Markovian dynamics, which consists in dividing the influence of the environment on the open system into a non-Markovian core, which encloses all the memory effects during the evolution, and a further Markovian component, representing the unidirectional leakage of information out of the non-Markovian core. The method is built on an equivalence theorem, recently derived in [1], which proves that a Gaussian bosonic environment evolving unitarily can be replaced by a Gaussian bosonic environment undergoing a Lindblad dynamics without changing the reduced dynamics of the open system interacting with it, if the first moments and the two-time correlation functions of the original and the auxiliary baths are the same at all times. Noticeably, as a special case, one recovers the well-known pseudomodes approach [2], directly extending it to a different form of the coupling. Starting from this result, a systematic procedure can be developed [3] to formulate auxiliary effective environments consisting of few bosonic degrees of freedom, typically a network of interacting harmonic oscillators, in this way reducing strongly the complexity of the model under study and then allowing for an efficient numerical investigation of the dynamics.

[1] D. Tamascelli, A. Smirne, S.F. Huelga, and M.B. Plenio, Nonperturbative Treatment of non-Markovian Dynamics of Open Quantum Systems, Phys. Rev. Lett. 120, 030402 (2018).
[2] B. M. Garraway, Nonperturbative decay of an atomic system in a cavity, Phys. Rev. A 55, 2290 (1997).
[3] F. Mascherpa, A. Smirne, P. Fernandez Acebal, S. Donadi, D. Tamascelli, S.F. Huelga, and M.B. Plenio, in preparation.


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