Modeling light-driven proton pumps in artificial photosynthetic reaction centers

Ghosh, Parthasarathi; Smirnov, Anatoly Yu.; Nori, Franco

doi:10.1063/1.3170939

Cited by 27 publications

(22 citation statements)

References 39 publications

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“…Quantum simulators will find numerous applications in diverse areas of physics and chemistry (Lanyon et al, 2010), and possibly even biology (Ghosh et al, 2009(Ghosh et al, , 2011a. Quantum simulation would lead to new results that cannot be otherwise simulated, and would also allow the testing of various theoretical models.…”

Section: Applicationsmentioning

confidence: 99%

Quantum simulation

2014

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Simulating quantum mechanics is known to be a difficult computational problem, especially when dealing with large systems. However, this difficulty may be overcome by using some controllable quantum system to study another less controllable or accessible quantum system, i.e., quantum simulation. Quantum simulation promises to have applications in the study of many problems in, e.g., condensed-matter physics, high-energy physics, atomic physics, quantum chemistry and cosmology. Quantum simulation could be implemented using quantum computers, but also with simpler, analog devices that would require less control, and therefore, would be easier to construct. A number of quantum systems such as neutral atoms, ions, polar molecules, electrons in semiconductors, superconducting circuits, nuclear spins and photons have been proposed as quantum simulators. This review outlines the main theoretical and experimental aspects of quantum simulation and emphasizes some of the challenges and promises of this fast-growing field.

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Section: Applicationsmentioning

confidence: 99%

Quantum simulation

2014

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“…The relationship between the non-equilibrium landscape and flux to energy pump as well as phase coherence was also studied in detail 30 . For quantum systems, the coherence, as a quantum signature, contributes to the transport 49,50 and the degree of the nonequilibriumness in addition to the populations 48 . This has been confirmed for quantum coherent excitation (charge) transport in light harvesting of photosynthetic reaction center 51,55 .…”

Section: Introductionmentioning

confidence: 99%

Curl flux, coherence, and population landscape of molecular systems: Nonequilibrium quantum steady state, energy (charge) transport, and thermodynamics

Zhang

Wang

2014

The Journal of Chemical Physics

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We established a theoretical framework in terms of the curl flux, population landscape and coherence for non-equilibrium quantum systems at steady state, through exploring the energy and charge transport in molecular processes. The curl quantum flux plays the key role in determining transport properties and the system reaches equilibrium when flux vanishes. The novel curl quantum flux reflects the degree of nonequilibriumness and the time-irreversibility. We found an analytical expression for the quantum flux and its relationship to the environmental pumping (non-equilibriumness quantified by the voltage away from the equilibrium) and the quantum tunnelling. Furthermore, we investigated another quantum signature, the coherence, quantitatively measured by the non-zero off diagonal element of the density matrix. Populations of states give the probabilities of individual states and therefore quantify the population landscape. Both curl flux and coherence depend on steady state population landscape. Besides the environment-assistance which can give dramatic enhancement of coherence and quantum flux with high voltage at a fixed tunnelling strength, the quantum flux is promoted by the coherence in the regime of small tunnelling while reduced by the coherence in the regime of large tunneling, due to the non-monotonic relationship between the coherence and tunneling. This is in contrast to the previously found linear relationship. For the systems coupled to bosonic (photonic and phononic) reservoirs the flux is significantly promoted at large voltage while for fermionic (electronic) reservoirs the flux reaches a saturation after a significant enhancement at large voltage due to the Pauli exclusion principle. In view of the system as a quantum heat engine, we studied the nonequilibrium thermodynamics and established the analytical connections of curl quantum flux to the transport quantities such as energy (charge) transfer efficiency (ETE or CTE), chemical reaction efficiency (CRE), energy dissipation, heat and electric currents observed in the experiments. We observed a perfect transfer efficiency in chemical reactions at high voltage (chemical potential difference). Our theoretical predicted behavior of the electric current with respect to the voltage is in good agreements with the recent experiments on electron transfer in single molecules.

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“…Our approach can describe two mechanisms of the redox-linked proton translocation across the membrane: (i) the static interaction site Q and (ii) the situation when the site Q diffuses between the sides of the membrane. The mechanism (i) roughly corresponds to the proton pump operating in cytochrome c oxidase (CcO) [3][4][5][6], whereas the design (ii) can be attributed to the redox loop mechanism, which is responsible for electron and proton transfers in the inner membrane of bacteria [7][8][9][10][11][12].…”

Section: Resultsmentioning

confidence: 99%

“…In the absence of strong Coulomb interaction between all sites, there is no need to introduce a complete set of electron and proton occupation states (as was done in our previous works, Refs. [6,[11][12][13]), which grows exponentially with the number of sites. Instead, we now divide the whole system into clusters of strongly coupled sites.…”

Section: Introductionmentioning

confidence: 99%

“…In the redox-loop mechanism of PMF generation, taking place in the nitrate respiratory chain of E. coli bacterium, the neutral shuttle, carrying both protons and electrons, crosses the membrane. Here, the charge accumulation occurs when electrons cross the membrane, just before embarking on the shuttle, and right after unloading from the shuttle [7][8][9][10][11][12]. It should be noted that the proton pump operating in the cytochrome c oxidase has no essential mechanically-moving parts, whereas the redox-loop mechanism is impossible without the molecular shuttle diffusing between the negative and the positive sides of the lipid membrane.…”

Section: Introductionmentioning

confidence: 99%

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Electrostatic models of electron-driven proton transfer across a lipid membrane

Smirnov¹,

Mourokh²,

Nori³

2011

J. Phys.: Condens. Matter

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We present two models for electron-driven uphill proton transport across lipid membranes, with the electron energy converted to the proton gradient via the electrostatic interaction. In the first model, associated with the cytochrome c oxidase complex in the inner mitochondria membranes, the electrostatic coupling to the site occupied by an electron lowers the energy level of the protonbinding site, making the proton transfer possible. In the second model, roughly describing the redox loop in a nitrate respiration of E. coli bacteria, an electron displaces a proton from the negative side of the membrane to a shuttle, which subsequently diffuses across the membrane and unloads the proton to its positive side. We show that both models can be described by the same approach, which can be significantly simplified if the system is separated into several clusters, with strong Coulomb interaction inside each cluster and weak transfer couplings between them. We derive and solve the equations of motion for the electron and proton creation/annihilation operators, taking into account the appropriate Coulomb terms, tunnel couplings, and the interaction with the environment. For the second model, these equations of motion are solved jointly with a Langevintype equation for the shuttle position. We obtain expressions for the electron and proton currents and determine their dependence on the electron and proton voltage build-ups, on-site charging energies, reorganization energies, temperature, and other system parameters. We show that the quantum yield in our models can be up to 100% and the power-conversion efficiency can reach 35%.

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Modeling light-driven proton pumps in artificial photosynthetic reaction centers

Cited by 27 publications

References 39 publications

Quantum simulation

Quantum simulation

Curl flux, coherence, and population landscape of molecular systems: Nonequilibrium quantum steady state, energy (charge) transport, and thermodynamics

Electrostatic models of electron-driven proton transfer across a lipid membrane

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