3,536 research outputs found
Raman Adiabatic Transfer of Optical States
We analyze electromagnetically induced transparency and light storage in an
ensemble of atoms with multiple excited levels (multi-Lambda configuration)
which are coupled to one of the ground states by quantized signal fields and to
the other one via classical control fields. We present a basis transformation
of atomic and optical states which reduces the analysis of the system to that
of EIT in a regular 3-level configuration. We demonstrate the existence of dark
state polaritons and propose a protocol to transfer quantum information from
one optical mode to another by an adiabatic control of the control fields
Distillation of Bell states in open systems
In this work we review the entire classification of 2x2 distillable states
for protocols with a finite numbers of copies. We show a distillation protocol
that allows to distill Bell states with non zero probability at any time for an
initial singlet in vacuum. It is shown that the same protocol used in non zero
thermal baths yields a considerable recovering of entanglement.Comment: 10 pages, 3 figure
The photoelectric effect without photons
Mathematical model of photoelectric effect without photon
Quantum Rabi model for N-state atoms
A tractable N-state Rabi Hamiltonian is introduced by extending the parity
symmetry of the two-state model. The single-mode case provides a few-parameter
description of a novel class of periodic systems, predicting that the ground
state of certain four-state atom-cavity systems will undergo parity change at
strong coupling. A group-theoretical treatment provides physical insight into
dynamics and a modified rotating wave approximation obtains accurate analytical
energies. The dissipative case can be applied to study excitation energy
transfer in molecular rings or chains.Comment: 5 pages, 3 figures + supplement (2 pages); to appear in Phys. Rev.
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Incoherent Mollow triplet
A counterpart of the Mollow triplet (luminescence lineshape of a two-level
system under coherent excitation) is obtained for the case of incoherent
excitation in a cavity. Its analytical expression, in excellent agreement with
numerical results, pinpoints analogies and differences between the conventional
resonance fluorescence spectrum and its cavity QED analogue under incoherent
excitation.Comment: 4 pages, 3 figure
Build-up of laser oscillations from quantum noise
Laser oscillation build up from quantum nois
Quantum-Classical Transition of Photon-Carnot Engine Induced by Quantum Decoherence
We study the physical implementation of the Photon Carnot engine (PCE) based
on the cavity QED system [M. Scully et al, Science, \textbf{299}, 862 (2003)].
Here, we analyze two decoherence mechanisms for the more practical systems of
PCE, the dissipation of photon field and the pure dephasing of the input atoms.
As a result we find that (I) the PCE can work well to some extent even in the
existence of the cavity loss (photon dissipation); and (II) the short-time
atomic dephasing, which can destroy the PCE, is a fatal problem to be overcome.Comment: 6 pages, 3 figure
Photonic band gap via quantum coherence in vortex lattices of Bose gases
We investigate the optical response of an atomic Bose-Einstein condensate
with a vortex lattice. We find that it is possible for the vortex lattice to
act as a photonic crystal and create photonic band gaps, by enhancing the
refractive index of the condensate via a quantum coherent scheme. If high
enough index contrast between the vortex core and the atomic sample is
achieved, a photonic band gap arises depending on the healing length and the
lattice spacing. A wide range of experimentally accessible parameters are
examined and band gaps in the visible region of the electromagnetic spectrum
are found. We also show how directional band gaps can be used to directly
measure the rotation frequency of the condensate.Comment: 4 pages, 4 figures, Final version to appear in PR
Quantum theory of a two-mode open-cavity laser
We develop the quantum theory of an open-cavity laser assuming that only two
modes compete for gain. We show that the modes interact to build up a
collective mode that becomes the lasing mode when pumping exceeds a threshold.
This collective mode exhibits all the features of a typical laser mode, whereas
its precise behavior depends explicitly on the openness of the cavity. We
approach the problem by using the density-matrix formalism and derive the
master equation for the light field. Our results are of particular interest in
the context random laser systems.Comment: 20 pages, 5 figure
Spectral Narrowing via Quantum Coherence
We have studied the transmission of an optically thick Rb vapor that is
illuminated by monochromatic and noise broaden laser fields in Lambda
configuration. The spectral width of the beat signal between the two fields
after transmission through the atomic medium is more than 1000 times narrower
than the spectral width of this signal before the medium.Comment: 4 pages, 4 figure
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