Macroscopic coherence of a single exciton state in an organic quantum wire

Dubin, F.; Melet, Romain; Barisien, Thierry; Grousson, R.; Legrand, Laurent; Schott, M.; Voliotis, Valia

doi:10.1038/nphys196

Cited by 159 publications

(141 citation statements)

References 16 publications

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“…However, diffusion is a statistical concept and loses its meaning when dealing with single excitons and donors in the nanoscopic volume of the NW. Considering the sub-wavelength dimensions of the present NWs, the exciton is, at the instant of its creation, a coherent excitation of the entire NW volume with its center-of-mass wavefunction extending throughout the length of the NW [13,14]. In NWs with a diameter d larger than the exciton Bohr radius a B , this effect has been directly observed by the quantization of the center-of-mass motion of the exciton normal to the NW axis [15] (for a theoretical description of the wavefunction and center-of-mass motion of excitons in NWs, see Ref.…”

Section: Resultsmentioning

confidence: 99%

Statistical analysis of excitonic transitions in single, free-standing GaN nanowires: Probing impurity incorporation in the poissonian limit

et al. 2010

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Single, free-standing GaN nanowires grown by plasma-assisted molecular-beam epitaxy have been investigated with low temperature micro-photoluminescence. The quantitative analysis of the luminescence spectra of around 100 nanowires revealed that each nanowire exhibits its own individual spectrum. A significant fraction of nanowires exclusively emits at energies corresponding to either surface-donor-bound or free excitons, demonstrating that optical properties of individual nanowires are determined by a few impurity atoms alone. The number of impurities per nanowire and their location within the nanowires varies according to Poissonian statistics.

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Section: Resultsmentioning

confidence: 99%

Statistical analysis of excitonic transitions in single, free-standing GaN nanowires: Probing impurity incorporation in the poissonian limit

et al. 2010

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“…The manifestation of vibronic coupling in spectra of molecular aggregates can therefore be used to measure exciton delocalization by relating the mean delocalization length of excitons to the ratio of the electronic photoluminescence band intensity (I 0-0 ) and the first vibronic band (I 0-1 ) 50,51 . Analysis of the photoluminescence ratio reveals the extraordinary coherent delocalization of the exciton along disorder-free polydiacetyelene chains 50,52 (Fig. 4), estimated to be 30-50 nm at 15 K.…”

Section: Measuring and Assessing Coherencementioning

confidence: 99%

Using coherence to enhance function in chemical and biophysical systems

Scholes

Fleming

Chen

et al. 2017

Nature

572

550

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“…where H is the Hamiltonian: 17) and Q( ) is an unspecified collision operator which describes the interaction of the particles with themselves and with their environment and accounts for dissipation mechanisms (ε is the scaled relaxation time). The key property that we request is that it drives the system to the local equilibria defined in the previous subsection.…”

Section: The Quantum Hydrodynamic Model (Qhd)mentioning

confidence: 99%

On quantum hydrodynamic and quantum energy transport models

Degond¹,

Gallego²,

Méhats³

2007

Communications in Mathematical Sciences

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Abstract. In this paper, we consider two recently derived models: the Quantum Hydrodynamic model (QHD) and the Quantum Energy Transport model (QET). We propose different equivalent formulations of these models and we use a commutator formula for stating new properties of the models. A gauge invariance lemma permits to simplify the QHD model for irrotational flows. We finish by considering the special case of a slowly varying temperature and we discuss possible approximations which will be helpful for future numerical discretizations.Key words. Density operator, quantum Liouville equation, quantum entropy, quantum local equilibrium, Quantum Hydrodynamics, Quantum Energy Transport, commutators, gauge invariance. subject classifications. 82C10, 82C70, 82D37, 81Q05, 81S05, 81S30, 81V70. IntroductionThis paper is the continuation of series of works investigating the properties and numerical approximations of quantum hydrodynamics and diffusion models based on the entropy principle. The growing interest of the scientific community towards quantum macroscopic models arises from the fact that they are computationally less expensive than microscopic models such as the Schrödinger or Wigner equation [3,4,9,30,32,33]. Simultaneously, collisions can be modeled without the use of quantum collision operators which are difficult to handle. The modeling of both quantum effects and collisions is particularly important for semiconductor devices where the active zone is small (sometimes less than 100 nanometers) and quantum effects are dominant while the access zones are constituted of electron reservoirs in which collisions are predominant and drive the system towards thermodynamic equilibrium. An example of such a device is the resonant tunneling diode [7] which constitutes a good candidate for testing models since it can be approximated by a one dimensional device.The route which has been usually followed for the derivation of quantum hydrodynamics and diffusion models consists in incorporating some "quantum" correction terms, often based on the Bohm potential, into classical fluid models. This Bohm potential appears naturally in the fluid formulation of the Schrödinger equation for a single particle evolving in an external potential V . One obtains this formulation through the use of the Madelung Transform, which consists in writing the wave function into an exponential form ψ = √ ne iS/ , where n is the density of mass, S is the phase and denotes the scaled Planck constant. Inserting this Ansatz in the Schrödinger equation, taking the real part and the gradient of the imaginary part, we recover the "Madelung equations" consisting in a pressureless Euler system involving an additional potential, called the Bohm potential

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Macroscopic coherence of a single exciton state in an organic quantum wire

Cited by 159 publications

References 16 publications

Statistical analysis of excitonic transitions in single, free-standing GaN nanowires: Probing impurity incorporation in the poissonian limit

Statistical analysis of excitonic transitions in single, free-standing GaN nanowires: Probing impurity incorporation in the poissonian limit

Using coherence to enhance function in chemical and biophysical systems

On quantum hydrodynamic and quantum energy transport models

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