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Register a new userSlicing the Fock space for state production and protection
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Added by
Gentil Dias de Moraes Neto
Publication date
2014
fields
Physics
and research's language is
English
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In this letter we present a protocol to engineer interactions confined to subspaces of the Fock space in trapped ions: we show how to engineer upper-, lower-bounded and sliced Jaynes-Cummings (JC) and anti-Jaynes-Cummings (AJC) Hamiltonians. The upper-bounded (lower-bounded) interaction acting upon Fock subspaces ranging from $leftvert 0rightrangle $ to $leftvert Mrightrangle $ ($leftvert Nrightrangle $ to$ infty$), and the sliced one confined to Fock subspace ranging from $leftvert Mrightrangle $ to $leftvert Nrightrangle $, whatever $M<N$. Whereas the upper-bounded JC or AJC interactions is shown to drive any initial state to a steady Fock state $leftvert Nrightrangle $, the sliced one is shown to produce steady superpositions of Fock states confined to the sliced subspace $left{ leftvert Nrightrangle text{,}leftvert N+1rightrangle right} $.
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We put forward a deterministic dissipative protocol to prepare phonon Fock states in nonlinear quantum optomechanical devices. The system is composed of a mechanical mode interacting with an optical field via radiation pressure, whereas the light mode is laser-driven in the resolved blue-sideband regime. To keep our results tractable, we have switched to an interaction picture in a displaced basis, where the effective Hamiltonian exhibits the selective photon-phonon interaction explicitly. After proper parameter adjustment and similarly to cavity-cooling schemes, the quantum evolution allows steering the mechanical degree of freedom to the desired Fock state by directing the optical excitations dynamically towards the target phonon state. The numerical results, including decoherence on both the mechanical and the optical degrees of freedom, show to be quite robust in the good- and bad-cavity regimes with fidelities exceeding $95%$. Lastly, characterization of the achieved nonclassicality, as well as the limitations and feasibility of our protocol under experimental parameters, are also analyzed.
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