uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Environmental design principles for efficient excitation energy transfer in dimer and trimer pigment-protein molecular aggregates and the relation to non-Markovianity
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
Stockholms universitet.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
(English)In: QuantumArticle in journal (Refereed) Submitted
Abstract [en]

Lately there has been an interest in studying the effects and mechanisms of environment-assisted quantum transport, especially in the context of excitation energy transfer (EET) in pigment-protein molecular aggregates. Since these systems can be seen as open quantum systems where the dynamics is within the non-Markovian regime, the effect of non-Markovianity on efficient EET as well as its role in preserving quantum coherence and correlations has also been investigated in recent works. In this study, we explore optimal environments for efficient EET between end sites in a number of dimer and trimer model pigment-protein molecular aggregates when the EET dynamics is modeled by the HEOM-method. For these optimal environmental parameters, we further quantify the non-Markovianity by the BLP-measure to elucidate its possible connection to efficient EET. We also quantify coherence in the pigment systems by means of the measure l1-norm of coherence to analyze its interplay with environmental effects when EET efficiency is maximal. Our aim is to investigate possible environmental design principles for achieving efficient EET in model pigment-protein molecular aggregates and to determine whether non-Markovianity is a possible underlying resource in such systems. We find that the structure of the system Hamiltonian (i.e., the pigment Hamiltonian parameter space) and especially, the relationship between the site excitation energies, determines whether one of two specific environmental regimes is the most beneficial in promoting efficient EET in these model systems. In the first regime, optimal environmental conditions are such that the EET dynamics in the system is left as coherent as possible. In the second regime, the most advantageous role of the environment is to drive the system towards equilibrium as fast as possible. In reality, optimal environmental conditions may involve a combination of these two effects. We cannot establish a relation between efficient EET and non-Markovianity, i.e., non-Markovianity cannot be regarded as a resource in the systems investigated in this study. 

Keywords [en]
Excitation energy transfer, Quantum coherence, Non-Markovianity
National Category
Natural Sciences
Research subject
Chemistry with specialization in Quantum Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-339462OAI: oai:DiVA.org:uu-339462DiVA, id: diva2:1175809
Available from: 2018-01-18 Created: 2018-01-18 Last updated: 2018-03-06
In thesis
1. Quantum Resources for Efficient Excitation Energy Transfer in Natural and Artificial Pigment-Protein Molecular Aggregates
Open this publication in new window or tab >>Quantum Resources for Efficient Excitation Energy Transfer in Natural and Artificial Pigment-Protein Molecular Aggregates
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Recently, long-lasting quantum effects in a number of photosynthetic complexes, which are pigment-protein molecular aggregates (PPMAs), were experimentally verified. These findings created an interest in trying to connect the known highly efficient excitation energy transfer (EET) in these systems to the existence of quantum effects such as quantum coherence and quantum correlations. It also raised the question of how these sensitive quantum effects can survive in such a macroscopic system.

This thesis explores the existence and possible role of quantum effects in the EET in PPMAs. These systems can be modeled as non-Markovian open quantum systems and quantum effects can be investigated and quantified by methods developed in quantum information theory.

Firstly, it is found that quantum nonlocal correlations in the EET in the Fenna-Matthews-Olson complex - a PPMA found in nature - are unlikely to exist when the initial excitation occurs in a natural manner. When the initial excitation occurs in an artificial manner by localization of the excitation on one pigment, nonlocal correlations exist on a short time scale. It is further found that in order for nonlocal correlations to be preserved in such a system, the excitation must be trapped on two pigments at the time and these pigments must not interact strongly with other pigments in the complex.

Secondly, it is shown that quantum coherence is not in general a resource for efficient EET in model systems consisting of a network of pigments; systems optimized with respect to the amount of coherence do not coincide with systems with optimal EET efficiency between two end-site pigments.

Thirdly, it is found that environmental effects and system-environment interactions can be tuned to optimize the EET efficiency in model PPMAs. The features of optimal environments highly depends on the structure of the pigment system and in particular, the relationship between the pigments excitation energies. It is further shown that a non-Markovian dynamics cannot be connected to an increased EET efficiency in these systems.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 120
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1622
Keywords
Quantum coherence, quantum correlations, quantum nonlocality, open quantum systems, non-Markovian dynamics
National Category
Natural Sciences
Research subject
Chemistry with specialization in Quantum Chemistry
Identifiers
urn:nbn:se:uu:diva-339469 (URN)978-91-513-0211-9 (ISBN)
Public defence
2018-03-09, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2018-02-16 Created: 2018-01-19 Last updated: 2018-03-07

Open Access in DiVA

No full text in DiVA

By organisation
Department of Chemistry - ÅngströmDepartment of Physics and Astronomy
Natural Sciences

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 25 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf