Nature of Quantum States Created by One Photon Absorption: Pulsed Coherent vs Pulsed Incoherent Light

Han, Alex C.; Shapiro, Moshe; Brumer, Paul

doi:10.1021/jp4023986

Cited by 16 publications

(18 citation statements)

References 29 publications

(58 reference statements)

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“…Therefore, an understanding of excitation under incoherent conditions is crucial. In such cases, the long time result of incoherent irradiation, using both quantum and classical light, leads to a mixed state of the system [3,4], a result discussed further in the literature in the context of photosynthetic light harvesting complexes [5][6][7]. However, work has been done, for example, on incoherent or noisy perturbations in quantum optics where some have found that incoherent or noisy electric fields can generate transient coherences in three level atoms [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Transient quantum coherent response to a partially coherent radiation field

Sadeq

Brumer

2014

The Journal of Chemical Physics

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The response of an arbitrary closed quantum system to a partially coherent electric field is investigated, with a focus on the transient coherences in the system. As a model we examine, both perturbatively and numerically, the coherences induced in a three level V system. Both rapid turn-on and pulsed turn-on effects are investigated. The effect of a long and incoherent pulse is also considered, demonstrating that during the pulse the system shows a coherent response which reduces after the pulse is over. Both the pulsed scenario and the thermally broadened CW case approach a mixed state in the long time limit, with rates dictated by the adjacent level spacings and the coherence time of the light, and via a mechanism that is distinctly difference from traditional decoherence. These two excitation scenarios are also explored for a minimal "toy" model of the electronic levels in pigment protein complex PC645 by both a collisionally broadened CW laser and by a noisy pulse, where unexpectedly long transient coherence times are observed and explained.The significance of environmentally induced decoherence is noted.

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Section: Introductionmentioning

confidence: 99%

Transient quantum coherent response to a partially coherent radiation field

Sadeq

Brumer

2014

The Journal of Chemical Physics

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“…This is distinctly different from the results of pulsed laser excitation, as most recently shown for coherent vs. incoherent excitation with the same spectrum [6]. Thus, the coherent pulsed laser experiments provide important insight into the nature of the system Hamiltonian and of the coupling of the system to the environment, but describe coherences in dynamics that is dramatically different than natural processes [4,5,[7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 75%

Open system perspective on incoherent excitation of light-harvesting systems

Pachón¹,

Botero²,

Brumer³

2017

J. Phys. B: At. Mol. Opt. Phys.

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The nature of excited states of open quantum systems produced by incoherent natural thermal light is analyzed based on a description of the quantum dynamical map. Natural thermal light is shown to generate long-lasting coherent dynamics because of (i) the super-Ohmic character of the radiation, and (ii) the absence of pure dephasing dynamics. In the presence of an environment, the long-lasting coherences induced by suddenly turned-on incoherent light dissipate and stationary coherences are established. As a particular application, dynamics in a subunit of the PC-645 light-harvesting complex is considered where it is further shown that aspects of the energy pathways landscape depend on the nature of the exciting light and number of chromophores excited.Specifically, pulsed laser and natural broadband incoherent excitation induce significantly different energy transfer pathways. In addition, we discuss differences in perspective associated with the eigenstate vs site basis, and note an important difference in the phase of system coherences when coupled to blackbody radiation or when coupled to a phonon background. Finally, an Appendix contains an open systems example of the loss of coherence as the turn on time of the light assumes natural time scales.

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“…As shown in Refs. [1,2], the initial conditions for excitation with an incoherent light source such as the sun are the productions of a set of individual phase-unrelated eigenstates. Hence, the incoherent dynamics discussed here always exists and is being induced by all light sources.…”

Section: ½E ð2þmentioning

confidence: 99%

“…In addition to this type of incoherent dynamics, there are coherent dynamics which follow excitations with coherent pulses, arising from the de-phasing of each ME with respect to all others. Such coherent pulsed excitations tell us, however, nothing about the situation with incoherent sources, where no coherent dynamics is exhibited [1,2].…”

Section: ½E ð2þmentioning

confidence: 99%

“…Introduction.-There is now growing evidence [1,2] that the coherent wave packet dynamics induced by ultrashort coherent pulses is quite different from the dynamics induced by incoherent sources, which in the long time limit results in the excitation of a multitude of phase-unrelated molecular eigenstate(s) (ME) [1][2][3]. Therefore, experiments using ultrafast coherent pulses that excite coherent wave packets and display long-lived electronic coherences [4][5][6][7][8][9], do not really tell us what happens when naturally occurring biological systems are excited by incoherent light, such as solar radiation.…”

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Quantum Dynamics Experienced by a Single Molecular Eigenstate Excited by Incoherent Light

Shapiro

2013

Phys. Rev. Lett.

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Contrary to conventional wisdom that all dynamics are a result of interference (or "dephasing") between many (at least two) energy eigenstates, we show that when a continuum of states is present, even a single molecular eigenstate undergoes "steady-state" quantum dynamics. Moreover, this type of dynamics can be initiated by incoherent (e.g., solar) light sources. Continua are invariably involved in molecular systems due to a variety of sources such as the ever present bath modes, spontaneously emitted photons; the detachment of electrons, or the dissociation of chemical bonds. Contrary to a single bound energy eigenfunction which is a real ("standing-waves") function that carries no flux and, hence, has no dynamics, a single (complex) continuum energy eigenfunction carries "steady-state" flux given by the group velocity of the energetically narrow wave packet it represents. When this energy eigenfunction is a multimode resonance embedded in a continuum via a chain of intramolecular couplings, this dynamics may be initiated by any (light) source, and is controlled, contrary to coherent wave packet dynamics, by the position of the resonance rather than its width.

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Nature of Quantum States Created by One Photon Absorption: Pulsed Coherent vs Pulsed Incoherent Light

Cited by 16 publications

References 29 publications

Transient quantum coherent response to a partially coherent radiation field

Transient quantum coherent response to a partially coherent radiation field

Open system perspective on incoherent excitation of light-harvesting systems

Quantum Dynamics Experienced by a Single Molecular Eigenstate Excited by Incoherent Light

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