Mathematical object that can be used to deter-mine the probability associated with the out-comes of any measurement that may be per-formed on a system prepared by the given preparation.
However, we do not need to measure all possible probability measurements to determine the state of a system.
: minimum number of probability measurements required to determine the state of a system, i.e., number of real parameters re-quired to specify the state.
: maximum number of states that can be reliably distinguished from one another in a single shot measurement.
subspace : If state of a system
a continuous reversible transformation on a system between anytwo pure states of that system: