Wg. Wang et al., MANIFESTATION OF DESTRUCTION OF QUANTUM INTEGRABILITY WITH EXPECTATION AND UNCERTAINTY VALUES OF QUANTUM OBSERVABLES, Physics letters. A, 190(5-6), 1994, pp. 377-381
A method to demonstrate destruction of quantum integrability is presen
ted. The method is based on the calculation (for systems with two degr
ees of freedom) of the expectation and uncertainty values of energy an
d another quantum observable which is conservative when the system is
integrable. Two kinds of avoided crossings can be shown clearly with t
his method.