Smilga, A.V.
(Symmetry, Integrability and Geometry: Methods and Applications, 2009)
We discuss the quantum dynamics of the PU oscillator, i.e. the system with the Lagrangian
L = ½ [ ¨q² - (Ω₁² + Ω₂²) ·q² + Ω₁²Ω₂²q ] (+ nonlinear terms).
When Ω₁ ≠ Ω₂, the free PU oscillator has a pure point spectrum ...