Search results for "78.20.Bh"
showing 5 items of 5 documents
Manipulating and squeezing the photon local density of states with plasmonic nanoparticle networks
2010
International audience; In this Brief Report, we show that when interconnected networks of gold particles are deposited onto a clean planar surface, they strongly modify the photonic local density of states LDOS in the immediate proximity of the self-assembled nanoparticles. They represent unique architectures for the subwavelength patterning of initially flat photonic LDOS. Moreover, we show that their local spectral signatures are well suited for the generation of sites able to enhance molecular fluorescence intensity.
Photon antibunching in the optical near field
2010
International audience; We show that a combination of the field-susceptibility technique with the optical Bloch equations gives access to the temporal evolution of the populations and coherences of any quantum system placed in the optical near field of a nanostructure. In particular, we show that the near-field evanescent states, confined around dielectric or plasmonic particles, can be used to modify and control the photon statistics of the quantum system. This theoretical scheme leads to second-order autocorrelation functions in good agreement with recent experimental measurements performed with nitrogen-vacancy center in diamond nanocrystals placed in interaction with gold nanoparticles.
Towards the time-optimal control of dissipative spin-1/2 particles in nuclear magnetic resonance
2011
International audience; We consider the time-optimal control of a spin 1/2 particle whose dynamics is governed by the Bloch equations with both longitudinal and transverse relaxation terms. We solve this control problem by using geometric optimal control techniques. We show the crucial role of singular extremals in the time-optimal synthesis. This role can mainly be attributed to the presence of dissipation. We also analyze the robustness of the optimal control sequence when both the maximum amplitude of the control field and the dissipative parameters are varied. Finally, we present an experimental implementation of the different solutions using techniques of Nuclear Magnetic Resonance.
Monotonically convergent optimal control theory of quantum systems with spectral constraints on the control field
2009
We propose a new monotonically convergent algorithm which can enforce spectral constraints on the control field (and extends to arbitrary filters). The procedure differs from standard algorithms in that at each iteration the control field is taken as a linear combination of the control field (computed by the standard algorithm) and the filtered field. The parameter of the linear combination is chosen to respect the monotonic behavior of the algorithm and to be as close to the filtered field as possible. We test the efficiency of this method on molecular alignment. Using band-pass filters, we show how to select particular rotational transitions to reach high alignment efficiency. We also con…
Ridge-enhanced optical transmission through a continuous metal film
2004
Optical transmission through a continuous (without holes) metal film with a periodic structure of metal or dielectric ridges on one or both interfaces was numerically studied. The dependencies of the transmission on the ridge width and height as well as the ridge arrangements on the opposite interfaces were investigated in weak- and strong-coupling regimes. The transmission enhancement was shown to depend on the relative position of the ridge gratings on the opposite interfaces of a film, confirming the role of resonant tunneling processes involving states of the surface polariton Bloch modes.