Polariton-polariton scattering: Exact results through a novel approach

Combescot, Monique; Dupertuis, M.‐A.; Betbeder‐Matibet, O.

doi:10.1209/0295-5075/79/17001

Cited by 37 publications

(54 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The exciton-exciton interaction potential V ex is associated with the Coulomb exchange scattering. The term V pae is a photon-assisted exchange scattering [24] and contributes to the reduction of the Rabi coupling, which is the reminiscence of the fermionic nature of the exciton [19]. In order to obtain a closed set of equations, we truncate the hierarchy by applying the following assumptions such as ψ † xψ xψ x…”

Section: Theorymentioning

confidence: 99%

Dephasing effects on coherent exciton-polaritons and the breakdown of the strong coupling regime

et al. 2015

View full text Add to dashboard Cite

Using femtosecond pump-probe spectroscopy, we identify excitation-induced dephasing as a major mechanism responsible for the breakdown of the strong coupling between excitons and photons in a semiconductor microcavity. The effects of dephasing are observed on the transmitted probe-pulse spectrum as a density-dependent broadening of the exciton-polariton resonances and the emergence of a third resonance at high excitation density. A striking asymmetry in the energy shift between the upper and the lower polaritons is also evidenced. Using the excitonic Bloch equations, we quantify the respective contributions to the energy shift of many-body effects associated with Coulomb fermion exchange and photon assisted exchange processes and the contribution to collisional broadening.

show abstract

Section: Theorymentioning

confidence: 99%

Dephasing effects on coherent exciton-polaritons and the breakdown of the strong coupling regime

et al. 2015

View full text Add to dashboard Cite

show abstract

“…where R X is the exciton Rydberg, and by −(8π − 315π 3 /512)(a X /L) 2 R X in 2D [23]. As a result, all the scatterings considered in Eq.…”

mentioning

confidence: 98%

“Gray” BCS Condensate of Excitons and Internal Josephson Effect

Combescot

2012

Phys. Rev. Lett.

View full text Add to dashboard Cite

It has been recently suggested that the Bose-Einstein condensate formed by excitons in the dilute limit must be dark, i.e., not coupled to photons. Here, we show that, under a density increase, the dark exciton condensate must acquire a bright component due to carrier exchange in which dark excitons turn bright. This however requires a density larger than a threshold which seems to fall in the forbidden region of the phase separation between a dilute exciton gas and a dense electron-hole plasma. The BCS-like condensation which is likely to take place on the dense side, must then have a dark and a bright component -which makes it "gray". It should be possible to induce an internal Josephson effect between these two coherent components, with oscillations of the photoluminescence as a strong proof of the existence for this "gray" BCS-like exciton condensate. The carrier mass being very light and Coulomb attraction quite reduced by the large crystal dielectric constant, the exciton Bohr radius a X is two orders of magnitude larger than the hydrogen atom Bohr radius. So, manybody effects controlled by the dimensionless parameterD where N is the exciton number, L the sample size and D the space dimension, can easily be made significant for N not too large. The most dramatic one is the Mott dissociation of excitons into an electronhole plasma [2] when the distance between two excitons is of the order of their size. Actually, η ∼ 1 most often fall in an instability region with phase separation between a dilute exciton phase and a dense electron-hole phase. In Si and Ge [3,4], this exciton dissociation is spontaneous at T = 0 because the lowest energy phase is the high density electron-hole plasma which is stabilized by the multivalley structure of the conduction band. In the case of direct gap semiconductors, a similar phase separation can occur at T = 0, but only under a density increase [5,6].The exciton composite nature also appears through the fact that excitons come in "bright" and "dark" states. Bright excitons, coupled to σ ± photons, are made of (∓1/2) conduction electrons and (±3/2) valence holes. Carrier exchanges however transform two opposite spin bright excitons (+1) and (-1) into two dark excitons (+2) and (-2), these (±2) excitons being made of (±1/2) conduction electrons and (±3/2) valence holes. These dark excitons have actually a lower energy than bright excitons. Indeed, in addition to the intraband Coulomb processes responsible for the dominant part of the exciton binding energy, interband Coulomb processes also exist in which one conduction electron returns to the valence band while one valence electron jumps in a conduction state. By just writing [7] that the electron conserves its spin when it changes from a conduction state with orbital momentum l = 0 to a valence state with orbital momentum l = 1, it is possible to show that the electron-hole pair which undergoes these interband processes must be bright. Since Coulomb interaction between electrons is repulsive, bright excitons thus have an energ...

show abstract

“…8,10 Polaritons are the exact eigenstates of one photon coupled to one exciton. A convenient way to write the photon-semiconductor coupling W ph-sc is…”

Section: Polaritonsmentioning

confidence: 99%

“…8,10 For normalized states ͗pЈ ͉ p͘ = ␦ p Ј p while ͗nЈ ͉ n͘ = ␦ n Ј n and ͗jЈ ͉ j͘ = ␦ j Ј j , these coefficients are such that…”

Section: Polaritonsmentioning

confidence: 99%

Closure relations for composite bosons: Difference between polaritons and Wannier or Frenkel excitons

Combescot

Dupertuis²

2008

Phys. Rev. B

View full text Add to dashboard Cite

We derive the closure relation for N polaritons made of three different types of excitons: bosonized excitons, Frenkel, or Wannier excitons. In the case of polaritons made of Wannier excitons, we show how this closure relation, which appears as nondiagonal, may reduce to the one of N elementary bosons, the photons, with its 1 / N! prefactor, or to the one of N Wannier excitons, with its ͑1 / N!͒ 2 prefactor. Widely different forms of closure relations are thus found depending on the composite bosons at hand. Comparison with closure relations of excitons, either bosonized or kept composite as Frenkel or Wannier excitons, allows us to discuss the influence of a reduction in the number of internal degrees of freedom, as well as the importance of the composite nature of the particles and the existence of fermionic components.

show abstract

Polariton-polariton scattering: Exact results through a novel approach

Cited by 37 publications

References 24 publications

Dephasing effects on coherent exciton-polaritons and the breakdown of the strong coupling regime

Dephasing effects on coherent exciton-polaritons and the breakdown of the strong coupling regime

“Gray” BCS Condensate of Excitons and Internal Josephson Effect

Closure relations for composite bosons: Difference between polaritons and Wannier or Frenkel excitons

Contact Info

Product

Resources

About