24 research outputs found
Nanosecond Dynamics of Single-Molecule Fluorescence Resonance Energy Transfer
Motivated by recent experiments on photon statistics from individual dye
pairs planted on biomolecules and coupled by fluorescence resonance energy
transfer (FRET), we show here that the FRET dynamics can be modelled by
Gaussian random processes with colored noise. Using Monte-Carlo numerical
simulations, the photon intensity correlations from the FRET pairs are
calculated, and are turned out to be very close to those observed in
experiment. The proposed stochastic description of FRET is consistent with
existing theories for microscopic dynamics of the biomolecule that carries the
FRET coupled dye pairs.Comment: 8 pages, 1 figure. accepted to J.Phys.Chem.
Nonclassical Imaging for a quantum search of trapped ions
We discuss a simple search problem which can be pursued with different
methods, either on a classical or on a quantum basis. The system is represented
by a chain of trapped ions. The ion to be searched is a member of that chain,
consists, however, of an isotopic species different to the others. It is shown
that the classical imaging may lead as fast to the final result as the quantum
imaging. However, for the discussed case the quantum method gives more
flexibility and higher precision when the number of ions considered in the
chain is increasing. In addition, interferences are observable even when the
distances between the ions is smaller than half a wavelength of the incident
light.Comment: 5 pages, 5 figure
Single microwave photon detection in the micromaser
High efficiency single photon detection is an interesting problem for many
areas of physics, including low temperature measurement, quantum information
science and particle physics. For optical photons, there are many examples of
devices capable of detecting single photons with high efficiency. However
reliable single photon detection of microwaves is very difficult, principally
due to their low energy. In this paper we present the theory of a cascade
amplifier operating in the microwave regime that has an optimal quantum
efficiency of 93%. The device uses a microwave photon to trigger the stimulated
emission of a sequence of atoms where the energy transition is readily
detectable. A detailed description of the detector's operation and some
discussion of the potential limitations of the detector are presented.Comment: 8 pages, 5 figure
Entanglement of bosonic modes of nonplanar molecules
Entanglement of bosonic modes of material oscillators is studied in the
context of two bilinearly coupled, nonlinear oscillators. These oscillators are
realizable in the vibrational-cum-bending motions of C-H bonds in
dihalomethanes. The bilinear coupling gives rise to invariant subspaces in the
Hilbert space of the two oscillators. The number of separable states in any
invariant subspace is one more than the dimension of the space. The dynamics of
the oscillators when the initial state belongs to an invariant subspace is
studied. In particular, the dynamics of the system when the initial state is
such that the total energy is concentrated in one of the modes is studied and
compared with the evolution of the system when the initial state is such
wherein the modes share the total energy. The dynamics of quantities such as
entropy, mean of number of quanta in the two modes and variances in the
quadratures of the two modes are studied. Possibility of generating maximally
entangled states is indicated.Comment: 21 pages, 6 figure
Multi-dimensional trio coherent states
We introduce a novel class of higher-order, three-mode states called
K-dimensional trio coherent states. We study their mathematical properties and
prove that they form a complete set in a truncated Fock space. We also study
their physical content by explicitly showing that they exhibit nonclassical
features such as oscillatory number distribution, sub-poissonian statistics,
Cauchy-Schwarz inequality violation and phase-space quantum interferences.
Finally, we propose an experimental scheme to realize the state with K=2 in the
quantized vibronic motion of a trapped ion.Comment: 17 pages, 12 figures, accepted for publication in J. Phys. A: Math.
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Femtosecond wave-packet dynamics in cesium dimers studied through controlled stimulated emission
Article on femtosecond wave-packet dynamics in cesium dimers studied through controlled stimulated emission