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Register a new userClassical Bethe Ansatz and Normal Forms in the Jaynes-Cummings Model
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The Jaynes-Cummings-Gaudin model describes a collection of $n$ spins coupled to an harmonic oscillator. It is known to be integrable, so one can define a moment map which associates to each point in phase-space the list of values of the $n+1$ conserved Hamiltonians. We identify all the critical points of this map and we compute the corresponding quadratic normal forms, using the Lax matrix representation of the model. The normal coordinates are constructed by a procedure which appears as a classical version of the Bethe Ansatz used to solve the quantum model. We show that only elliptic or focus-focus singularities are present in this model, which provides an interesting example of a symplectic toric action with singularities. To explore these, we study in detail the degeneracies of the spectral curves for the $n=1$ and $n=2$ cases. This gives a complete picture for the image of the momentum map (IMM) and the associated bifurcation diagram. For $n=2$ we found in particular some lines of rank 1 which lie, for one part, on the boundary of the IMM, where they behave like an edge separating two faces, and which go, for another part, inside the IMM.
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The theory of non-Hermitian systems and the theory of quantum deformations have attracted a great deal of attention in the last decades. In general, non-Hermitian Hamiltonians are constructed by a textit{ad hoc} manner. Here, we study the (2+1) Dirac oscillator and show that in the context of the $kappa$--deformed Poincare-Hopf algebra its Hamiltonian is non-Hermitian but having real eigenvalues. The non-Hermiticity steams from the $kappa$-deformed algebra. From the mapping in [Bermudez textit{et al.}, Phys. Rev. A textbf{76}, 041801(R) 2007], we propose the $kappa$-JC and $kappa$--AJC models, which describe an interaction between a two-level system with a quantized mode of an optical cavity in the $kappa$--deformed context. We find that the $kappa$--deformation modifies the textit{Zitterbewegung} frequencies and the collapse and revival of quantum oscillations. In particular, the total angular momentum in the $z$--direction is not conserved anymore, as a direct consequence of the deformation.
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