  We describe some applications of quantum information theory to the analysis
of quantum limits on measurement sensitivity. A measurement of a weak force
acting on a quantum system is a determination of a classical parameter
appearing in the master equation that governs the evolution of the system;
limitations on measurement accuracy arise because it is not possible to
distinguish perfectly among the different possible values of this parameter.
Tools developed in the study of quantum information and computation can be
exploited to improve the precision of physics experiments; examples include
superdense coding, fast database search, and the quantum Fourier transform.
