The combination of chain-mapping and tensor-network techniques provides a powerful tool for the numerically exact simulation of open quantum systems interacting with structured environments. However, these methods suffer from a quadratic scaling with the physical simulation time, and therefore, they become challenging in the presence of multiple environments. This is particularly true when fermionic environments, well-known to be highly correlated, are considered. In this work, we first illustrate how a thermo-chemical modulation of the spectral density allows replacing the original fermionic environments with equivalent, but simpler, ones. Moreover, we show how this procedure reduces the number of chains needed to model multiple environments. We then provide a derivation of the fermionic Markovian closure construction, consisting of a small collection of damped fermionic modes undergoing a Lindblad-type dynamics and mimicking a continuum of bath modes. We describe, in particular, how the use of the Markovian closure allows for a polynomial reduction of the time complexity of chain-mapping based algorithms when long-time dynamics are needed.

Spectral density modulation and universal Markovian closure of fermionic environments / D. Ferracin, A. Smirne, S.F. Huelga, M.B. Plenio, D. Tamascelli. - In: THE JOURNAL OF CHEMICAL PHYSICS. - ISSN 0021-9606. - 161:17(2024 Nov 07), pp. 174114.1-174114.23. [10.1063/5.0226723]

Spectral density modulation and universal Markovian closure of fermionic environments

D. Ferracin
Primo
;
A. Smirne
Secondo
;
D. Tamascelli
Ultimo
2024

Abstract

The combination of chain-mapping and tensor-network techniques provides a powerful tool for the numerically exact simulation of open quantum systems interacting with structured environments. However, these methods suffer from a quadratic scaling with the physical simulation time, and therefore, they become challenging in the presence of multiple environments. This is particularly true when fermionic environments, well-known to be highly correlated, are considered. In this work, we first illustrate how a thermo-chemical modulation of the spectral density allows replacing the original fermionic environments with equivalent, but simpler, ones. Moreover, we show how this procedure reduces the number of chains needed to model multiple environments. We then provide a derivation of the fermionic Markovian closure construction, consisting of a small collection of damped fermionic modes undergoing a Lindblad-type dynamics and mimicking a continuum of bath modes. We describe, in particular, how the use of the Markovian closure allows for a polynomial reduction of the time complexity of chain-mapping based algorithms when long-time dynamics are needed.
Settore PHYS-04/A - Fisica teorica della materia, modelli, metodi matematici e applicazioni
   Quantum hyperpolarisation for ultrasensitive nuclear magnetic resonance and imaging
   HyperQ
   European Commission
   Horizon 2020 Framework Programme
   856432

   Spin based quantum computer and simulator (SPINUS)
   SPINUS
   European Commission
   Horizon Europe Framework Programme
   101135699
7-nov-2024
https://doi.org/10.1063/5.0226723
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/1116828
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