Probing post-measurement entanglement without post-selection

Understand

We study the problem of observing quantum collective phenomena emerging from large numbers of measurements.

• These phenomena are difficult to observe in conventional experiments because, in order to distinguish the effects of measurement from dephasing, it is necessary to post-select on sets of measurement outcomes whose Born probabilities are exponentially small in the number of measurements performed.
• An unconventional approach, which avoids this exponential `post-selection problem', is to construct cross-correlations between experimental data and the results of simulations on classical computers.
• However, these cross-correlations generally have no definite relation to physical quantities.