Measuring polynomial functions of states (pp401-408)
        Todd A. Brun
          doi: https://doi.org/10.26421/QIC4.5-6
Abstracts: In this paper I show that any $m$th-degree polynomial function of the elements of the density matrix $\rho$ can be determined by finding the expectation value of an observable on $m$ copies of $\rho$, without performing state tomography. Since a circuit exists which can approximate the measurement of any observable, in principle one can find a circuit which will estimate any such polynomial function by averaging over many runs. I construct some simple examples and compare these results to existing procedures.
Key words:  measurement, information measures