Uncertainty revisited: Novel tradeoffs in quantum measurement

There is, so to speak, uncertainty about uncertainty – that is, over the interpretation of how Heisenberg's uncertainty principle describes the extent of disturbance to one observable when measuring another. More specifically, the confusion is between the fact that, as Heisenberg first intuited, the measurement of one observable on a quantum state necessarily disturbs another incompatible observable, and the fact that on the other hand the indeterminacy of the outcomes when either one or the other observable is measured is bounded. Recently, Dr. Cyril Branciard at The University of Queensland precisely quantified the former by showing how it is possible to approximate the joint measurement of two observables, albeit with the introduction of errors with respect to the ideal measurement of each. Moreover, the scientist characterized the disturbance of an observable induced by the approximate measurement of another one, and derived a stronger error-disturbance relation for this scenario.