Multi-wave-mixing of two-dimensional excitons in semiconductors

Decoherence suppression of excitons in semiconductor using sequential femtosecond pulses

“…Under ideal p pulse irradiation, only the EWM signal in the Àk 1 +2k 2 À2k 3 +2k 4 direction remains and the four-wave mixing signal, for example, vanishes. In our experiment, however, the pulse areas Y (¼ m=_ R E dt, where m is exciton dipole moment and E is pulse amplitude) are smaller than p [6]; thus, other MWM signals also appear, and the intensity of the EWM signal is reduced. Here, note that the decoherence process is not influenced by the pulse areas [7].…”

“…First, we perform the SWM experiment by the heterodyne detection in order to confirm whether we can obtain the same result. In the inhomogeneous broadening case, the SWM echo signal appears at 2t 23 away from the arriving time of pulse #1 under the condition of t 23 4t 12 [6,8]. Fig.…”

Decoherence Control Of Excitons By A Sequence Of Pulses

“…In this article, the pulse with the k i vector will be denoted as #i, and the relative delay time between #i and #j is written as T ij . In the case of SWM, the echo signal appears 2T 23 away from the arriving time of the #1 pulse, because of inhomogeneous broadening in our sample [4]. In the SWM experiments, T 23 was scanned with a fixed value of T 12 and the signal in the k 1 -2k 2 +2k 3 direction was observed.…”

Decoherence suppression of excitons by bang–bang control

“…In the case of SWM, the second pulse works as a p pulse like the second pulse of FWM. In the inhomogeneous broadening case, the SWM echo signal appears 2t 23 away from the arriving time of ]1 pulse under the condition of t 23 4t 12 [5]. Therefore, the decay profile of coherence is observed by changing t 23 .…”