1,741 research outputs found
Coherence-controlled transparency and far-from-degenerate parametric gain in a strongly-absorbing Doppler-broadened medium
An inversionless gain of anti-Stokes radiation above the oscillation
threshold in an optically-dense far-from-degenerate double-Lambda
Doppler-broadened medium accompanied by Stokes gain is predicted. The outcomes
are illustrated with numerical simulations applied to sodium dimer vapor.
Optical switching from absorption to gain via transparency controlled by a
small variation of the medium and of the driving radiation parameters which are
at a level less than one photon per molecule is shown. Related video/audio
clips see in: A.K. Popov, S.A. Myslivets, and T.F. George, Optics Express Vol.
7, No 3, 148 (2000)(http://epubs.osa.org/oearchive/source/22947.htm) or
download: http://kirensky.krasn.ru/popov/opa/opa.htmComment: 4 pages, 3 eps figures, to be published in Optics Letters, vol.25, No
18 (2000), minor style changes and reference correctio
Opto-mechanical transducers for long-distance quantum communication
We describe a new scheme to interconvert stationary and photonic qubits which
is based on indirect qubit-light interactions mediated by a mechanical
resonator. This approach does not rely on the specific optical response of the
qubit and thereby enables optical quantum interfaces for a wide range of solid
state spin and charge based systems. We discuss the implementation of quantum
state transfer protocols between distant nodes of a large scale network and
evaluate the effect of the main noise sources on the resulting state transfer
fidelities. For the specific examples of electronic spin qubits and
superconducting charge qubits we show that high fidelity quantum communication
protocols can be implemented under realistic experimental conditions.Comment: Version as accepted by PR
Quantum theory of resonantly enhanced four-wave mixing: mean-field and exact numerical solutions
We present a full quantum analysis of resonant forward four-wave mixing based
on electromagnetically induced transparency (EIT). In particular, we study the
regime of efficient nonlinear conversion with low-intensity fields that has
been predicted from a semiclassical analysis. We derive an effective nonlinear
interaction Hamiltonian in the adiabatic limit. In contrast to conventional
nonlinear optics this Hamiltonian does not have a power expansion in the fields
and the conversion length increases with the input power. We analyze the
stationary wave-mixing process in the forward scattering configuration using an
exact numerical analysis for up to input photons and compare the results
with a mean-field approach. Due to quantum effects, complete conversion from
the two pump fields into the signal and idler modes is achieved only
asymptotically for large coherent pump intensities or for pump fields in
few-photon Fock states. The signal and idler fields are perfectly quantum
correlated which has potential applications in quantum communication schemes.
We also discuss the implementation of a single-photon phase gate for continuous
quantum computation.Comment: 10 pages, 11 figure
Quantum magnetism with multicomponent polar molecules in an optical lattice
We consider bosonic dipolar molecules in an optical lattice prepared in a
mixture of different rotational states. The 1/r^3 interaction between molecules
for this system is produced by exchanging a quantum of angular momentum between
two molecules. We show that the Mott states of such systems have a large
variety of non-trivial spin orderings including a state with ordering wave
vector that can be changed by tilting the lattice. As the Mott insulating phase
is melted, we also describe several exotic superfluid phases that will occur
Collective Phase Chaos in the Dynamics of Interacting Oscillator Ensembles
We study chaotic behavior of order parameters in two coupled ensembles of
self-sustained oscillators. Coupling within each of these ensembles is switched
on and off alternately, while the mutual interaction between these two
subsystems is arranged through quadratic nonlinear coupling. We show
numerically that in the course of alternating Kuramoto transitions to synchrony
and back to asynchrony, the exchange of excitations between two subpopulations
proceeds in such a way that their collective phases are governed by an
expanding circle map similar to the Bernoulli map. We perform the Lyapunov
analysis of the dynamics and discuss finite-size effects.Comment: 19 page
- …