Effect of disorder potential on the dynamics of resonantly excited incoherent free exciton-polariton fluids in high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Q</mml:mi></mml:math> GaAs microcavitiesстатья
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Аннотация:The temporal behavior of the lower polariton (LP) distribution in the reciprocal space, 𝑛LP(𝑘), and formation of long-range spatial coherence are investigated in a nonequilibrium incoherent LP fluid generated resonantly with picosecond optical pulses at 2 K in a high-𝑄 planar GaAs/AlAs microcavity with 12 InGaAs quantum wells. The dynamics of 𝑛LP(𝑘) is found to be independent of excitation density and well described within the framework of linear Schrödinger equations taking into account random potential disorder, 𝛿𝐸LP, and finite lifetime of LPs, up to LP density 𝑛LP(𝑡=0)=7×1010cm−2 (3.5 orders of magnitude greater than the threshold density of Bose-Einstein condensation for LPs). This is explained by the smallness of the ratios of LP interaction energy to both the mean kinetic energy and potential disorder. The contribution of interparticle interaction to the formation of spatial coherence in the LP fluid is insignificant at 𝐸int≪𝛿𝐸LP, but becomes noticeable already at 𝐸int≈0.2𝛿𝐸LP, despite the fact that its effect on the 𝑘 distribution of LPs remains insignificant. Coherence length 𝐿𝑐 in LP fluid with 𝑛LP(𝑡=0)=2 and 7×1010cm−2 in the region with 𝛿𝐸LP=0.15 meV at 𝑡=160 ps increases to 4.1 and 5.3µm, respectively, whereas in an incoherent Bose gas with the same 𝑛LP(𝑘) it is equal to 3.6µm.