Hardy Expt

The "quantum measurement problem" has always been the central philosophical conundrum of quantum mechanics, but in recent years, new technologies and new potential applications such as quantum information processing have turned the area of quantum measurement into a respectable (read:experimental) discipline as well.  It turns out that far from being the ideal to which all experimental measurements should aspire, the textbook paradigm of projective measurement is merely an approximation to one sort of laboratory measurement -- and not always a very good one, at that.   I will present several examples of how our current ideas on quantum measurement go beyond the usual textbook treatments, using examples from our entangled-photon and ultracold-atoms laboratories in Toronto.  In particular, I will talk about "weak measurement" and whether or not quantum mechanics allows us to use present observations to draw conclusions about quantities we didn't directly measure in the past.