Let 
be a 
-algebra, then a state is a positive linear functional on
of norm 1.
State
This entry contributed by Mohammad Sal Moslehian
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References
Murphy, G. J. C*-Algebras and Operator Theory. New York: Academic Press, 1990.Referenced on Wolfram|Alpha
StateCite this as:
Weisstein, Eric W., with contributions by Mohammad Sal Moslehian. "State." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/State.html