Quantum integrability in systems with finite number of levels
  We consider the problem of defining quantum integrability in systems with finite number of energy levels starting from commuting matrices and construct new general classes of such matrix models with a given number of commuting partners. We argue that if the matrices depend on a (real) parameter, one can define quantum integrability from this feature alone, leading to specific results such as exact solvability, Poissonian energy level statistics and to level crossings. 
Emil A. Yuzbashyan and B. Sriram Shastry
cond-mat.str-el math-ph math.MP quant-ph