Lev VAIDMAN

Weak value of a quantum variable was introduced by Aharonov, Albert and Vaidman in 1988 as an outcome of a standard quantum measurement with weakened coupling performed on an ensemble of pre and postselected  systems. A common interpretation of the weak value is a conditional expectation value (there are even claims that it is not necessarily a quantum concept). I will argue that it has a deeper meaning as a robust property of a single pre and postselected system. Experimental demonstrations supporting this claim will be reported and some controversies about weak values will be discussed.  An application of a new paradigm of the past of a quantum particle as the weak value of a projection for a novel alignment method will be reported.