Nonequilibrium quantum systems: Divergence between global and local descriptions

Pedro D. Manrique, Ferney Rodríguez, Luis Quiroga, Neil F Johnson

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Even photosynthesis - the most basic natural phenomenon underlying life on Earth - involves the nontrivial processing of excitations at the pico- and femtosecond scales during light-harvesting. The desire to understand such natural phenomena, as well as interpret the output from ultrafast experimental probes, creates an urgent need for accurate quantitative theories of open quantum systems. However it is unclear how best to generalize the well-established assumptions of an isolated system, particularly under nonequilibrium conditions. Here we compare two popular approaches: a description in terms of a direct product of the states of each individual system (i.e., a local approach) versus the use of new states resulting from diagonalizing the whole Hamiltonian (i.e., a global approach). The main difference lies in finding suitable operators to derive the Lindbladian and hence the master equation. We show that their equivalence fails when the system is open, in particular under the experimentally ubiquitous condition of a temperature gradient. By solving for the steady state populations and calculating the heat flux as a test observable, we uncover stark differences between the formulations. This divergence highlights the need to establish rigorous ranges of applicability for such methods in modeling nanoscale transfer phenomena - including during the light-harvesting process in photosynthesis.

Original languageEnglish (US)
Article number615727
JournalAdvances in Condensed Matter Physics
Volume2015
DOIs
StatePublished - Feb 23 2015

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photosynthesis
divergence
nonequilibrium conditions
equivalence
heat flux
temperature gradients
formulations
operators
probes
output
products
excitation

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Nonequilibrium quantum systems : Divergence between global and local descriptions. / Manrique, Pedro D.; Rodríguez, Ferney; Quiroga, Luis; Johnson, Neil F.

In: Advances in Condensed Matter Physics, Vol. 2015, 615727, 23.02.2015.

Research output: Contribution to journalArticle

Manrique, Pedro D. ; Rodríguez, Ferney ; Quiroga, Luis ; Johnson, Neil F. / Nonequilibrium quantum systems : Divergence between global and local descriptions. In: Advances in Condensed Matter Physics. 2015 ; Vol. 2015.
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