123 research outputs found
Enhanced Nonlinear Generation in a Three-Level Medium with Spatially Dependent Coherence
We consider a method for efficient parametric generation of a laser pulse. A
single laser field is injected to a three-level medium which has two lower
states and one excited state. The lower states are prepared initially in a
position-dependent coherent superposition state. It is shown that by proper
choice of the position dependence of the superposition along the direction of
propagation, the incoming field can be converted completely to a new field.Comment: Revtex4 document, 3 pages, 2 figure
Localizing an atom via quantum interference
Published versio
Fast quantum information transfer with superconducting flux qubits coupled to a cavity
We present a way to realize quantum information transfer with superconducting
flux qubits coupled to a cavity. Because only resonant qubit-cavity interaction
and resonant qubit-pulse interaction are applied, the information transfer can
be performed much faster, when compared with the previous proposals. This
proposal does not require adjustment of the qubit level spacings during the
operation. Moreover, neither uniformity in the device parameters nor exact
placement of qubits in the cavity is needed by this proposal.Comment: 6 pages, 3 figure
Fluorescence control through multiple interference mechanisms
Published versio
Ab initio, nonperturbative calculations of laser-induced continuum structure in helium
Published versio
Advanced control with a Cooper-pair box: stimulated Raman adiabatic passage and Fock-state generation in a nanomechanical resonator
The rapid experimental progress in the field of superconducting nanocircuits
gives rise to an increasing quest for advanced quantum-control techniques for
these macroscopically coherent systems. Here we demonstrate theoretically that
stimulated Raman adiabatic passage (STIRAP) should be possible with the
quantronium setup of a Cooper-pair box. The scheme appears to be robust against
decoherence and should be realizable even with the existing technology. As an
application we present a method to generate single-phonon states of a
nanomechnical resonator by vacuum-stimulated adiabatic passage with the
superconducting nanocircuit coupled to the resonator
Transparency of a short laser pulse via decay interference in a closed V-type system
Published versio
Propagation and nonlinear generation dynamics in a coherently prepared four-level system
Published versio
The influence of density of modes on dark lines in spontaneous emission
We study two distinct multi-level atomic models in which one transition is
coupled to a Markovian reservoir, while another linked transition is coupled to
a non-Markovian reservoir. We show that by choosing appropriately the density
of modes of the non-Markovian reservoir the spontaneous emission to the
Markovian reservoir is greatly altered. The existence of `dark lines' in the
spontaneous emission spectrum in the Markovian reservoir due to the coupling to
specific density of modes of the non-Markovian reservoir is also predicted.Comment: 11 pages including 9 figure
Qualitative aspects of the entanglement in the three-level model with photonic crystals
This communication is an enquiry into the circumstances under which
concurrence and phase entropy methods can give an answer to the question of
quantum entanglement in the composite state when the photonic band gap is
exhibited by the presence of photonic crystals in a three-level system. An
analytic approach is proposed for any three-level system in the presence of
photonic band gap. Using this analytic solution, we conclusively calculate the
concurrence and phase entropy, focusing particularly on the entanglement
phenomena. Specifically, we use concurrence as a measure of entanglement for
dipole emitters situated in the thin slab region between two semi-infinite
one-dimensionally periodic photonic crystals, a situation reminiscent of planar
cavity laser structures. One feature of the regime considered here is that
closed-form evaluation of the time evolution may be carried out in the presence
of the detuning and the photonic band gap, which provides insight into the
difference in the nature of the concurrence function for atom-field coupling,
mode frequency and different cavity parameters. We demonstrate how fluctuations
in the phase and number entropies effected by the presence of the
photonic-band-gap. The outcomes are illustrated with numerical simulations
applied to GaAs. Finally, we relate the obtained results to instances of any
three-level system for which the entanglement cost can be calculated. Potential
experimental observations in solid-state systems are discussed and found to be
promising.Comment: 28 pages, 10 figures: Accepted in Applied Physics B: Laser and Optic
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