Room-temperature coherent revival in an ensemble of quantum dots

We demonstrate the hallmark concept of periodic collapse and revival coherence in a room-temperature ensemble quantum dots (QDs) form 1.5-mm-long optical amplifier. Femtosecond excitation pulses induce coherent interactions with number discrete homogeneous QD subgroups within an inhomogeneously broadened ensemble, which interfere constructively to (CR). The amplitude decay CR is dictated by linewidth, thus enabling its extraction double-pulse Ramsey-type experiment. more common photon echo technique also invoked yields same linewidth provided that both experiments use bias. A dephasing time ${T}_{2}$ longer than 5 ps extracted. This record long for testifies high quality InAs/InP QDs used experiments. Measured electrical bias temperature dependencies transverse relaxation times (${T}_{2}$ ${T}_{2}^{*}$) enable determination two main decoherence mechanisms: carrier-carrier carrier-phonon scatterings.