Comment on ‘Initial states of qubit–environment models leading to conserved quantities’
Chi‐Fai Lo
Recently, Gardas and Dajka (2013 J. Phys. A: Math. Theor. 46 235301) proposed a theoretical scheme on how to prepare a proper initial state of a composite qubit–boson system which could assure no energy exchange between the two subsystems. For illustration, they applied the proposed scheme to both the Jaynes–Cummings model and the multi-photon Rabi model. However, it has already been rigorously proven that the k -photon Rabi model for k > 2 does not have eigenstates in the Hilbert space spanned by the eigenstates of the corresponding k -photon Jaynes–Cummings model and that the two-photon Rabi model has a discrete eigenenergy spectrum with normalizable eigenstates only if the coupling strength is smaller than a critical value. Hence, the proposed theoretical scheme is not applicable to the multi-photon Rabi model.
Journal of Physics A Mathematical and Theoretical•Apr 2, 2014•1 citation