Fröhlich polarons from 0D to 3D: concepts and recent developments

Devreese, J. T.

doi:10.1088/0953-8984/19/25/255201

Cited by 50 publications

(42 citation statements)

References 135 publications

(406 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this letter, the formation of polaron provides an unambiguous evidence for the invalidity of Huang-Rhys formulism (adiabatic theory) in dealing with exciton-LO phonon interaction in QD. Recently, T. J. Devreese et al [31,32] emphasize that the effect of non-adiabaticity should be taken into account to interpret the surprisingly enhancement of the phonon replicas in the PL spectra, and it is also expected that this method can pave the way for a deeper understanding of our results. In the strong coupling regime (e.g., high temperature), we also believe that our results are important to the understanding of the carrier decoherence and relaxation process in QD [1,2,3,4].…”

mentioning

confidence: 85%

Direct observation of excitonic polaron in InAs/GaAs quantum dots

Gong

Chen

et al. 2010

EPL

View full text Add to dashboard Cite

Excitonic polaron is directly demonstrated for the first time in InAs/GaAs quantum dots with photoluminescence method. A new peak (s ′ ) below the ground state of exciton (s) comes out as the temperature varies from 4.2 K to 285 K, and a huge anticrossing energy of 31 meV between s ′ and s is observed at 225 K, which can only be explained by the formation of excitonic polaron.The results also provide a strong evidence for the invalidity of Huang-Rhys formulism in dealing with carrier-longitudinal optical phonon interaction in quantum dot. Instead, we propose a simple two-band model, and it fits the experimental data quite well. The reason for the finding of the anticrossing is also discussed.PACS numbers: 60.20. Kr, 78.67.Hc Electron-phonon interaction is a very important ingredient determining the physical properties of semiconductors, such as phonon-assisted hot carrier relaxation process [1,2], light absorption and emission process [3,4]. For electron-longitudinal optical (LO) interaction in the weak polar system (e.g., GaAs, α c = 0.067), the welldocumented Huang-Rhys model always gives good explanation in bulk material. However, in quantum dot (QD), this interaction is greatly enhanced owing to the discrete nature of energy levels with spacing comparable to the energy of LO phonon. Both theoretical and experimental findings show that it may have entered the strong coupling regime [3,5,6,7], which means that an accurate description of this interaction system should be the hybridation of electron state and the phonon state, thus the polaron as a new ground state will be formed [8]. Similar conclusion can also be drawn to hole and exciton interacting with LO phonons in QD.Although Huang-Rhys parameter S and Fröhlich coupling constant α c are both related to the average number of LO phonons, while the irreversible emission of LO phonons (0.1 ∼ 1 ps) provides an efficient channel for energy relaxation [9], the formation of polaron will suppress the LO phonon contribution to the carrier decoherence process and hence leads to long polaron lifetime [5,6,7] and everlasting oscillation of survival probability [5,10,11].In experiments, far-infrared (FIR) absorption results have evidenced the formation of electron-LO [10,11], hole-LO [12] and exciton-LO[13] induced magnetopolaron in QDs under ultra-high magnetic field (up to ∼ 28 T) at about 4 K, and anticrossing between the polaron levels differing by one LO phonon[6] is found. How- * email: cfli@ustc.edu.cn ever, hampered by the large full width at half maximum (FWHM), no direct observation of excitonic polaron has yet been reported.In this letter, as we vary the temperature from 4 K to 285 K, the FWHM of the s peak decreases sharply, thus we can directly observe the excitonic polaron without applying magnetic field. It is shown that at low temperature, the exciton-LO phonon interaction is weak and may be explained within the framework of Huang-Rhys model and enhanced S value is obtained. But at high temperature, due to the increasing of coupling strength, exciton...

show abstract

mentioning

confidence: 85%

Direct observation of excitonic polaron in InAs/GaAs quantum dots

Gong

Chen

et al. 2010

EPL

View full text Add to dashboard Cite

show abstract

“…The angulon represents aq uantum rotor dressedb y af ield of many-particle excitations, [1][2][3] and in principle can be thought of as arotational analogue of the well-studied polaron quasiparticle. [4][5][6][7][8] It was demonstrated, however,t hat the non-Abelian algebra used to describe quantum rotations, as well as the discrete spectrum of the rotor's eigenvalues,render the angulon physics substantially different from that of any other impurity problem. [1][2][3] For instance, once placed inside as uperfluid, the molecular states become" dressed" by ac loud of phonon excitations, ap rocess which lowers the molecular energy.W hile this effect also takes place forp olarons, in the case of molecules the magnitude of the shift depends on the rotational state the molecule is in.…”

Section: Introductionmentioning

confidence: 99%

Libration of Strongly‐Oriented Polar Molecules inside a Superfluid

Redchenko

Lemeshko

2016

ChemPhysChem

View full text Add to dashboard Cite

We study a polar molecule immersed into a superfluid environment, such as a helium nanodroplet or a Bose-Einstein condensate, in the presence of an intense electrostatic field. We show that coupling of the molecular pendular motion, induced by the field, to the fluctuating bath leads to formation of pendulons -spherical harmonic librators dressed by a field of many-particle excitations. We study the behavior of the pendulon in a broad range of molecule-bath and molecule-field interaction strengths, and reveal that its spectrum features series of instabilities which are absent in the field-free case of the angulon quasiparticle. Furthermore, we show that an external field allows to fine-tune the positions of these instabilities in the molecular rotational spectrum. This opens the door to detailed experimental studies of redistribution of orbital angular momentum in many-particle systems.

show abstract

“…These experimental results indicate that it is essential to include into consideration the non-adiabaticity of the ex-ph interaction [21,40] leading to a phononmediated coupling of different bare exciton levels, even if they are separated by energies quite different from the optical phonon energy. A step towards understanding the new effects arising from such coupling was made in recent works [7,[122][123][124] and it seems that it is possible to explain the essence of the above experimental findings even within the minimal model considered in these works, illustrated in Fig.…”

Section: Effect Of Non-adiabaticitymentioning

confidence: 97%

“…3.1), both in their spectral positions and relative intensities [21]. Although both the strong Stokes shift and apparently large intensity of the first phonon satellite (relative to the zero phonon line) can be characteristic of the QD size distribution and not of a single dot [35], these results indicate that the ex-ph interaction in QDs must be considered carefully and the adiabatic approximation (leading to the emission spectra described by the Franck-Condon progression) can be insufficient [21,40].…”

Section: Introductionmentioning

confidence: 96%

“…In particular, it means that multi-phonon (virtual) processes can be important and the ex-ph interaction in QDs must be treated in a non-perturbative way, even for the moderate values of the coupling constants coming out from the calculations. An important ingredient to be included in the theory is the non-adiabaticity of this interaction [21,40] leading to a phononmediated coupling of different electronic levels, even if they are separated by an energy quite different from the optical phonon energy [7]. In this contribution we discuss the theoretical issues of the ex-ph interaction, polaron formation and its dynamics in nearly spherical QDs.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Exciton-phonon interaction in semiconductor nanocrystals

Vasilevskiy

Semiconductor Nanocrystal Quantum Dots

View full text Add to dashboard Cite

Fröhlich polarons from 0D to 3D: concepts and recent developments

Cited by 50 publications

References 135 publications

Direct observation of excitonic polaron in InAs/GaAs quantum dots

Direct observation of excitonic polaron in InAs/GaAs quantum dots

Libration of Strongly‐Oriented Polar Molecules inside a Superfluid

Exciton-phonon interaction in semiconductor nanocrystals

Contact Info

Product

Resources

About