Recently Paulus and his team had reported observation of interference in time. http://physicsweb.org/articles/news/9/3/1/1?rss=2.0 http://arxiv.org/pdf/quant-ph/0503165 It is a marvellous experiment. But, it appears the work is not fully explained and the experimental results need careful analysis. For example, the observation of high contrast fringes are observed for pi/2 phase of optical light pulse resulting in electron detection in the +ve direction and poor contrast fringes in the –ve direction. The contrast of the fringes is plotted as a function of electron energy. The mechanism of conversion of single atto second pulse into electron emission is not explained. Unless that is done, the mechanism of conversion of two atto second pulses in to electron in +ve and –ve direction will remain unclear. In particular, the reasoning, as to why the variation of contrast as a function of electron energy should be interpreted as observation of interference in time. Does any one have an explanation.