Delayed choice experiments: An analysis in forward time
In this article, we present a detailed analysis of two famous delayed choice experiments: Wheeler's classic gedanken-experiment and the delayed quantum eraser. It shows that the outcomes of both experiment can be fully explained on the basis of the information collected during the experiments using textbook quantum mechanics only. At no point in the analysis, information from the future is needed to explain what happens next. In fact more is true: for both experiments we show, in a strictly mathematical way, that a modified version in which the time-ordering of the steps is changed to avoid the delayed choice leads to exactly the same final state. In this operational sense, the scenarios are completely equivalent in terms of conclusions that can be drawn from their outcomes.