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Vitanov, N V

Publications and source records attributed to Vitanov, N V.

7 records

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DOE OSTI2011

Microscopic description of dissipative dynamics of a level-crossing transition

We analyze the effect of a dissipative bosonic environment on the Landau-Zener-Stueckelberg-Majorana (LZSM) level crossing model by using a microscopic approach to derive the relevant master equation. For an environment at zero temperature and weak dissipation, our microscopic approach confirms the independence of the survival probability on the decay rate that has been predicted earlier by the simple phenomenological LZSM model. For strong decay the microscopic approach predicts a notable increase of the survival probability, which signals dynamical decoupling of the initial state. Unlike the phenomenological model, our approach makes it possible to study the dependence of the system dynamics on the temperature of the environment. In the limit of very high temperature we find that the dynamics is characterized by a very strong dynamical decoupling of the initial state--the temperature-induced quantum Zeno effect.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Wireless adiabatic power transfer

Research Highlights: > Efficient and robust mid-range wireless energy transfer between two coils. > The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. > Wireless energy transfer is insensitive to any resonant constraints. > Wireless energy transfer is insensitive to noise in the neighborhood of the coils. - Abstract: We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Stimulated Raman adiabatic passage in a {Lambda} system in the presence of quantum noise

We exploit a microscopically derived master equation for the study of stimulated Raman adiabatic passage in the presence of spontaneous decay from the intermediate state toward the initial and final states and compare our results with the predictions obtained from a phenomenological model used previously [P. A. Ivanov, N. V. Vitanov, and K. Bergmann, Phys. Rev. A 72, 053412 (2005)]. It is shown that our approach predicts a much higher efficiency for counterintuitively ordered pulses, while no significant difference between the two approaches is found for intuitively ordered pulses. These features are readily explained in the dressed-state picture.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2010

Dephasing effects on stimulated Raman adiabatic passage in tripod configurations

We present an analytic description of the effects of dephasing processes on stimulated Raman adiabatic passage in a tripod quantum system. To this end, we develop an effective two-level model. Our analysis makes use of the adiabatic approximation in the weak dephasing regime. An effective master equation for a two-level system formed by two dark states is derived, where analytic solutions are obtained by utilizing the Demkov-Kunike model. From these, it is found that the fidelity for the final coherent superposition state decreases exponentially for increasing dephasing rates. Depending on the pulse ordering and for adiabatic evolution, the pulse delay can have an inverse effect.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2010

Stimulated Raman adiabatic passage in an open quantum system: Master equation approach

A master equation approach to the study of environmental effects in the adiabatic population transfer in three-state systems is presented. A systematic comparison with the non-Hermitian Hamiltonian approach [Vitanov and Stenholm, Phys. Rev. A 56, 1463 (1997)] shows that, in the weak-coupling limit, the two treatments lead to essentially the same results. In contrast, in the strong-damping limit the predictions are quite different: In particular, the counterintuitive sequences in the STIRAP scheme turn out to be much more efficient than expected before. This point is explained in terms of quantum Zeno dynamics.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2010

Scalable quantum search using trapped ions

We propose a scalable implementation of Grover's quantum search algorithm in a trapped-ion quantum information processor. The system is initialized in an entangled Dicke state by using adiabatic techniques. The inversion-about-average and oracle operators take the form of single off-resonant laser pulses. This is made possible by utilizing the physical symmetries of the trapped-ion linear crystal. The physical realization of the algorithm represents a dramatic simplification: each logical iteration (oracle and inversion about average) requires only two physical interaction steps, in contrast to the large number of concatenated gates required by previous approaches. This not only facilitates the implementation but also increases the overall fidelity of the algorithm.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2010

Casimir-Polder interaction between an atom and a periodic nanostructure

We present a theory for the calculation of the Casimir-Polder potential experienced by an atom near the surface of a nanostructure. The potential is found by means of the electrodynamic Green's tensor based on a layer-multiple-scattering method. We calculate the distance law of the Casimir-Polder potential for a monolayer of metallic and dielectric nanospheres arranged periodically on a square lattice. We find, in particular, that the Casimir-Polder potential for a metallic nanostructure is practically independent of the type of the metal from which the nanostructure is made. Also, the Casimir-Polder potential shows an exponential decay close to the nanostructure and an inverse power-law decrease away from it wherein the exponent depends on the size of the spheres of the nanostructure.

77 NANOSCIENCE AND NANOTECHNOLOGY↗