2 research outputs found
Nonlinear coherent states for the Susskind-Glogower operators
We construct nonlinear coherent states for the Susskind-Glogower operators by
the application of the displacement operator on the vacuum state. We also
construct nonlinear coherent states as eigenfunctions of a Hamiltonian
constructed with the Susskind-Glogower operators. We generalize the solution of
the eigen- function problem to an arbitrary |mi initial condition. To analyze
the obtained results, we plot the Husimi Q function, the photon number
probability distribution and the Mandel Q-parameter. For both cases, we find
that the constructed states exhibit interesting nonclassical features, such as
amplitude squeezing and quantum interferences due to a self-splitting into two
coherent-like states. Additionally, we show that non- linear coherent states
may be modeled by propagating light in semi-infinite arrays of optical fibers.Comment: 22 pages, 8 figures, Conference Quantum Optics V, Published as:
REVISTA MEXICANA DE F\'ISICA S 57 (3) 133-14
Decoherence in quantum lossy systems: superoperator and matrix techniques
Due to the unavoidably dissipative interaction between quantum systems with their environments, the decoherence flows inevitably into the systems. Therefore, to achieve a better understanding on how decoherence affects on the damped systems, a fundamental investigation of master equation seems to be required. In this regard, finding out the missed information which has been lost due to irreversibly of the dissipative systems, is also of practical importance in quantum information science. Motivating by these facts, in this work we want to use superoperator and matrix techniques, by which we are able to illustrate two methods to obtain the explicit form of density operators corresponding to damped systems at arbitrary temperature T ≥ 0. To establish the potential abilities of the suggested methods, we apply them to deduce the density operator of some practical well-known quantum systems. Using the superoperator techniques, at first we obtain the density operator of a damped system which includes a qubit interacting with a single-mode quantized field within an optical cavity. As the second system, we study the decoherence of a quantized field within an optical damped cavity. We also use our proposed matrix method to study the decoherence of a system which includes two qubits in the interaction with each other via dipole-dipole interaction and at the same time with a quantized field in a lossy cavity. The influences of dissipation on the decoherence of dynamical properties of these systems are also numerically investigated. At last, the advantages of the proposed superoperator techniques in comparison with matrix method are explained