Access

Letter

Nature Physics 4, 700–705 (1 September 2008) | doi:10.1038/nphys1034

Observation of Bogoliubov excitations in exciton-polariton condensates

S. Utsunomiya , L. Tian , G. Roumpos , C. W. Lai , N. Kumada , T. Fujisawa , M. Kuwata-Gonokami , A. L|[ouml]|ffler , S. H|[ouml]|fling , A. Forchel & Y. Yamamoto

Einstein|[rsquo]|s 1925 paper predicted the occurrence of Bose–Einstein condensation (BEC) in an ideal gas of non-interacting bosonic particles. However, particle–particle interaction and peculiar excitation spectra are keys for understanding BEC and superfluidity physics.