Generalized quantum measurements (positive operator valued measures or probability operator measures) are important for optimally extracting information for quantum communication and computation. The standard realization via the Neumark extension requires extensive resources in the form of operations in an extended Hilbert space. For an arbitrary measurement, we show how to construct a binary search tree with a depth logarithmic in the number of possible outcomes. This could be implemented experimentally by coupling the measured quantum system to a probe qubit which is measured, and then iterating.

• Received 31 December 2007

DOI:https://doi.org/10.1103/PhysRevA.77.052104