Abstract Following the concept of Hanamura the Bose formalism of Usui is used to investigate the collective properties of a dense gas of excitons. The correlation self‐energy for excitons is calculated with the help of a special concept of pure excitonic screening. The dielectric function and the collective modes are studied in detail. It is shown, that the consideration of excited exciton states leads to a lowering of the 1s exciton level with increasing exciton density. Furthermore the damping of the 1s exciton due to exciton–exciton collisions is investigated.Abstract Following the concept of Hanamura the Bose formalism of Usui is used to investigate the collective properties of a dense gas of excitons. The correlation self‐energy for excitons is calculated with the help of a special concept of pure excitonic screening. The dielectric function and the collective modes are studied in detail. It is shown, that the consideration of excited exciton states leads to a lowering of the 1s exciton level with increasing exciton density. Furthermore the damping of the 1s exciton due to exciton–exciton collisions is investigated.

physica status solidi (b)Oct 1, 198415 citations

Collective properties of excitons in semiconductors

Leonid V. Keldysh, Andrey Nikolaevich Kozlov

WORLD SCIENTIFIC eBooksNov 1, 2023150 citations

Collective excitations of graphene excitons being in the Bose-Einstein condensate state

Pavel A. Andreev

Bose-Einstein condensation of the excitons in graphene is considered. We suggested the model spinor equation for neutral particles with short range interaction described the microscopic graphene excitons dynamic. Using this equation we derived quantum hydrodynamic equations for description of collective properties of excitons in graphene, particularly for the case when excitons being in the Bose-Einstein condensate (BEC) state. The dispersion of collective excitations in graphene excitons BEC is studied. We shown that frequency of collective excitations is proportional to the square root of the wave vector module: $ω\sim \sqrt{k}$ .Bose-Einstein condensation of the excitons in graphene is considered. We suggested the model spinor equation for neutral particles with short range interaction described the microscopic graphene excitons dynamic. Using this equation we derived quantum hydrodynamic equations for description of collective properties of excitons in graphene, particularly for the case when excitons being in the Bose-Einstein condensate (BEC) state. The dispersion of collective excitations in graphene excitons BEC is studied. We shown that frequency of collective excitations is proportional to the square root of the wave vector module: $ω\sim \sqrt{k}$.

arXiv:1201.6553Jan 31, 20120 citations

Collective state of interwell excitons in GaAs/AlGaAs double quantum wells under pulse resonance excitation

A. V. Larionov, Vladislav B. Timofeev, J. M. Hvam +1 more

The time evolution and kinetics of photoluminescence (PL) spectra of interwell excitons in double GaAs/AlGaAs quantum wells ( n-i-n structures) have been investigated under the pulse resonance excitation of intrawell 1sHH excitons using a pulsed tunable laser. It is found that the collective exciton phase arises with a time delay relative to the exciting pulse (several nanoseconds), which is due to density and temperature relaxation to the equilibrium values. The origination of the collective phase of interwell excitons is accompanied by a strong narrowing of the corresponding photoluminescence line (the line width is about 1.1 meV), a superlinear rise in its intensity, a long time in the change of the degree of circular polarization, a displacement of the PL spectrum toward lower energies (about 1.5 meV) in accordance with the filling of the lowest state with the exciton Bose condensate, and a significant increase in the radiative decay rate of the condensed phase. The collective exciton phase arises at temperatures T <6 K and interwell exciton densities n =3×10 10 cm −2 . Coherent properties of the collective phase of interwell excitons and experimental manifestations of this coherence are discussed.The time evolution and kinetics of photoluminescence (PL) spectra of interwell excitons in double GaAs/AlGaAs quantum wells ( n-i-n structures) have been investigated under the pulse resonance excitation of intrawell 1sHH excitons using a pulsed tunable laser. It is found that the collective exciton phase arises with a time delay relative to the exciting pulse (several nanoseconds), which is due to density and temperature relaxation to the equilibrium values. The origination of the collective phase of interwell excitons is accompanied by a strong narrowing of the corresponding photoluminescence line (the line width is about 1.1 meV), a superlinear rise in its intensity, a long time in the change of the degree of circular polarization, a displacement of the PL spectrum toward lower energies (about 1.5 meV) in accordance with the filling of the lowest state with the exciton Bose condensate, and a significant increase in the radiative decay rate of the condensed phase. The collective exciton phase arises at temperatures T <6 K and interwell exciton densities n =3×10 10 cm −2 . Coherent properties of the collective phase of interwell excitons and experimental manifestations of this coherence are discussed.

Journal of Experimental and Theoretical Physics LettersFeb 1, 200222 citations

ω\sim \sqrt{k}