<s>[INST] In quantum mechanics, an observable is a property of a physical system that can be measured with a simple open-and-shut instrument (e.g. position, momentum, energy). Consider a two-state system. A convenient choice of basis is { U | Up>, D | Down>}. One observable in this system is a Hermitian operator. One member of the Hermitian Operator can be in the form of 2sigma3+3Identity operator. The 2sigma3 can be measured with some simple instrument by two-state system and correspondingly Identity operator can be measured indirectly.[/INST]