Asao Arai
Necessary and Sufficient Conditions for a Hamiltonian with Discrete Eigenvalues to Have 
Time Operators
(207K, PDF)

ABSTRACT.  We present new classes of time operators of a Hamiltonian $H$ (a self-adjoint operator) with discrete eigenvalues which 
may be degenerate. 
Moreover we formulate 
necessary and sufficient conditions for $H$ to have time operators, determining 
the general form of them. 
 As corollaries, 
non-existence theorems of time operators for some classes of $H$ are derived.