  The author summarizes the Quantum Bayesian viewpoint of quantum mechanics,
developed originally by C. M. Caves, R. Schack, and himself. It is a view
crucially dependent upon the tools of quantum information theory. Work at the
Perimeter Institute for Theoretical Physics continues the development and is
focused on the hard technical problem of a finding a good representation of
quantum mechanics purely in terms of probabilities, without amplitudes or
Hilbert-space operators. The best candidate representation involves a
mysterious entity called a symmetric informationally complete quantum
measurement. Contemplation of it gives a way of thinking of the Born Rule as an
addition to the rules of probability theory, applicable when one gambles on the
consequences of interactions with physical systems. The article ends by
outlining some directions for future work.
