1,721,020 research outputs found
Dynamical properties of two coupled quantum cavities with single-mode amplification
Full text linkCoupled optical cavities provide one of the simplest possible schemes to engineer the interaction of bosonic modes. This paper investigates a two-mode model where, in addition to the usual mode coupling, the presence of an amplification term associated to one of the modes triggers an unexpectedly rich dynamical scenario. The resulting nontrivial model is diagonalized by implementing the dynamical-algebra method, a group-theoretic approach which allows one to determine the stability diagram of the model Hamiltonian in terms of the two mode frequencies for given values of the interaction and amplification parameters. The mode interaction significantly modifies the simple amplification effect of the noninteracting model causing the separation of the
unstable domain (where the amplification takes place) into two subdomains, one of which is stable, features no amplification effect, and exhibits an extension controlled by the interaction parameter. The analysis of stability properties is corroborated by the fully analytic study of the energy spectrum which exhibits the transition from a discrete to a continuous structure whenever the system undergoes the transition from a stable region to an unstable region where the amplification effect occurs. This scenario is further confirmed by the calculation of the time evolution of the mode populations
Dynamic instability of axially loaded shafts in the Mathieu map
No full textIt is shown that theMathieu eigenvalues can be straightforwardly utilized to study the instability regions of an axially loaded simply supported shaft, the shaft being modeled as a continuous rotating beam. When a harmonic axial load is taken into account, the equation of motion of the system, here written according to the Lagrangian formulation of continuous systems, proves to be the Mathieu equation. It follows that the conditions for the stable or unstable motion of the shaft can be graphically investigated once the operation line corresponding to an actual rotating shaft is drawn in the Mathieu ma
Two-boson algebra and quantum computing with Josephson-like systems
No full textOur investigation concerns the class of Josephson-like systems, sharing the same nonlinear Hamiltonian. Among the latter a Josephson junction with an external biasing circuit is considered. We diagonalize the fully nonlinear Hamiltonian (in the superconductive regime of the junction) in the Fock space of the TBHA (two-boson Heisenberg algebra) and prove that such algebra leads quite naturally to the theoretical realization of codewords and logical operators: the codewords are defined as the even and odd coherent states of the TBHA, while the logical operators are expressed in terms of operators in the same algebra. Our theoretical construction corresponds to a continuous variable quantum computation scheme; the continuous variables are identified in terms of the physical operators of the junction. The link between this scheme and the technique of fermionization of bosonic systems is also discussed
Quantum computational schemes generated by k-boson algebras
No full textIt is shown that a multiboson (k-boson) algebra can be conveniently utilized to generate a k-dimensional computational basis. The single qukit logical operators are given ∀k and two different constructions of the CNOT gate are presente
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