排序方式: 共有36条查询结果,搜索用时 15 毫秒
31.
Stimulated scattering of indirect excitons in coupled quantum wells: signature of a degenerate Bose-gas of excitons. 总被引:1,自引:0,他引:1
L V Butov A L Ivanov A Imamoglu P B Littlewood A A Shashkin V T Dolgopolov K L Campman A C Gossard 《Physical review letters》2001,86(24):5608-5611
We observe and analyze strongly nonlinear photoluminescence kinetics of indirect excitons in GaAs/AlGaAs coupled quantum wells at low bath temperatures, > or = 50 mK. The long recombination lifetime of indirect excitons promotes accumulation of these Bose particles in the lowest energy states and allows the photoexcited excitons to cool down to temperatures where the dilute 2D gas of indirect excitons becomes statistically degenerate. Our main result--a strong enhancement of the exciton scattering rate to the low-energy states with increasing concentration of the indirect excitons--reveals bosonic stimulation of exciton scattering, which is a signature of a degenerate Bose-gas of excitons. 相似文献
32.
The importance of the effect of phosphate rock depends on the chemical form of phosphorus in which this element is combined. The paper presents the results of inorganic and organic forms of phosphorus in the phosphate rock from Mazidag-Derik, Semikan deposit located at Mardin city at SE Anatolia of Turkey. Total phosphorus concentration in the rock is an average 18.5%. The inorganic phosphorus mean % contents were 99.98% for studied sedimentary phosphate rock. Speciation of inorganic phosphorus was carried out using a method based on sequential extractions of the sedimentary phosphate rock each releasing four forms of inorganic phosphorus: loosely sorbed phosphorus, phosphorus bound to aluminium (P-Al), phosphorus bound to calcium (P-Ca) and phosphorus bound to iron (P-Fe). Calcium bound phosphorus is the dominant form of inorganic phosphorus in the studied sedimentary phosphate rock. Aluminium bound phosphorus is the second, iron bound phosphorus is the third most prevailing form. Loosely bound phosphorus is present in the lowest amounts. Analyses of phosphorus forms in sedimentary phosphate rock using a UV spectrophotometric method and ICP-AES are reported here. For the phosphorus the two methods give the same results and the concentrations are in good agreement with the reference values. 相似文献
33.
Ö zlem Imamoglu Olav K. Richter 《Proceedings of the American Mathematical Society》2006,134(4):995-1001
We determine an explicit formula for a Rankin-Cohen bracket for Siegel modular forms of degree on a certain subgroup of the symplectic group. Moreover, we lift that bracket via a Poincaré series to a Siegel cusp form on the full symplectic group.
34.
High-speed properties of a phase-modulation scheme based on electromagnetically induced transparency
Recently a cross-phase modulation scheme that yields giant Kerr nonlinearities by use of an electromagnetically induced transparency (EIT) was proposed [Schmidt and Imamoglu, Opt. Lett. 21, 1936 (1996)]. We analyze the high-speed properties of this scheme for short-pulse propagation. We discuss the relevant losses in this system and show that for short pulses one-photon losses are dominant. We demonstrate that over the entire bandwidth the attainable phase shift in an EIT scheme with a quasi-cw coupling field is orders of magnitude higher than in a conventional three-level scheme or in EIT schemes, in which matched pulses are used to create the transparency. 相似文献
35.
36.
Türeci HE Hanl M Claassen M Weichselbaum A Hecht T Braunecker B Govorov A Glazman L Imamoglu A von Delft J 《Physical review letters》2011,106(10):107402
We study a quantum quench for a semiconductor quantum dot coupled to a fermionic reservoir, induced by the sudden creation of an exciton via optical absorption. The subsequent emergence of correlations between spin degrees of freedom of dot and reservoir, culminating in the Kondo effect, can be read off from the absorption line shape and understood in terms of the three fixed points of the single-impurity Anderson model. At low temperatures the line shape is dominated by a power-law singularity, with an exponent that depends on gate voltage and, in a universal, asymmetric fashion, on magnetic field, indicative of a tunable Anderson orthogonality catastrophe. 相似文献