1,113 research outputs found
Interaction of bimodal fields with few-level atoms in cavities and traps
The spectacular experimental results of the last few years in cavity quantum
electrodynamics and trapped ions research has led to very high level laboratory
performances. Such a stimulating situation essentially stems from two decisive
advancements. The first is the invention of reliable protocols for the
manipulation of single atoms. The second is the ability to produce desired
bosonic environments on demand. These progresses have led to the possibility of
controlling the form of the coupling between individual atoms and an arbitrary
number of bosonic modes. As a consequence, fundamental matter-radiation
interaction models like, for instance, the JC model and most of its numerous
nonlinear multiphoton generalizations, have been realized or simulated in
laboratory and their dynamical features have been tested more or less in
detail. This topical paper reviews the state of the art of the theoretical
investigations and of the experimental observations concerning the dynamical
features of the coupling between single few-level atoms and two bosonic modes.
In the course of the paper we show that such a configuration provides an
excellent platform for investigating various quantum intermode correlation
effects tested or testable in the cavity quantum electrodynamics and trapped
ion experimental realms. In particular we discuss a mode-mode correlation
effect appearing in the dynamics of a two-level atom quadratically coupled to
two bosonic modes. This effect, named parity effect, consists in a high
sensitivity to the evenness or oddness of the total number of bosonic
excitations.Comment: Topical Review. To appear on J. Mod. Op
The rotating wave system-reservoir coupling: limitations and meaning in the non-Markovian regime
This paper deals with the dissipative dynamics of a quantum harmonic
oscillator interacting with a bosonic reservoir. The Master Equations based on
the Rotating Wave and on the Feynman-Vernon system--reservoir couplings are
compared highlighting differences and analogies. We discuss quantitatively and
qualitatively the conditions under which the counter rotating terms can be
neglected. By comparing the analytic solution of the heating function relative
to the two different coupling models we conclude that, even in the weak
coupling limit, the counter rotating terms give rise to a significant
contribution in the non--Markovian short time regime. The main result of this
paper is that such a contribution is actually experimentally measurable and
thus relevant for a correct description of the system dynamics.Comment: 14 pages, 3 figure
Misbelief and misunderstandings on the non--Markovian dynamics of a damped harmonic oscillator
We use the exact solution for the damped harmonic oscillator to discuss some
relevant aspects of its open dynamics often mislead or misunderstood. We
compare two different approximations both referred to as Rotating Wave
Approximation. Using a specific example, we clarify some issues related to
non--Markovian dynamics, non--Lindblad type dynamics, and positivity of the
density matrix.Comment: 6 pages, 2 figures, added info: submitted to J. Opt. B: Quantum and
Semiclass. Opt., Special Issue of the 10th Central European Workshop on
Quantum Optics, reference added, discussion clarifie
Quantum theory of heating of a single trapped ion
The heating of trapped ions due to the interaction with a {\it quantized
environment} is studied {\it without performing the Born-Markov approximation}.
A generalized master equation local in time is derived and a novel theoretical
approach to solve it analytically is proposed. Our master equation is in the
Lindblad form with time dependent coefficients, thus allowing the simulation of
the dynamics by means of the Monte Carlo Wave Function (MCWF) method.Comment: 4 pages, 3 figure
Simulating open quantum systems with trapped ions
This paper focuses on the possibility of simulating the open system dynamics of a paradigmatic model, namely the damped harmonic oscillator, with single trapped ions. The key idea consists in using a controllable physical system, i.e. a single trapped ion interacting with an engineered reservoir, to simulate the dynamics of other open systems usually difficult to study. The exact dynamics of the damped harmonic oscillator under very general conditions is firstly derived. Some peculiar characteristic of the system's dynamics are then presented. Finally a way to implement with trapped ion the specific quantum simulator of interest is discussed
Entanglement oscillations in non-Markovian quantum channels
We study the non-Markovian dynamics of a two-mode bosonic system interacting
with two uncorrelated thermal bosonic reservoirs. We present the solution to
the exact microscopic Master equation in terms of the quantum characteristic
function and study in details the dynamics of entanglement for bipartite
Gaussian states. In particular, we analyze the effects of short-time
system-reservoir correlations on the separability thresholds and show that the
relevant parameter is the reservoir spectral density. If the frequencies of the
involved modes are within the reservoir spectral density entanglement persists
for a longer time than in a Markovian channel. On the other hand, when the
reservoir spectrum is out of resonance short-time correlations lead to a faster
decoherence and to the appearance of entanglement oscillations.Comment: 5 pages, 2 figures, published versio
Non-Markovian quantum jumps
Open quantum systems that interact with structured reservoirs exhibit
non-Markovian dynamics. We present a quantum jump method for treating the
dynamics of such systems. This approach is a generalization of the standard
Monte Carlo Wave Function (MCWF) method for Markovian dynamics. The MCWF method
identifies decay rates with jump probabilities and fails for non-Markovian
systems where the time-dependent rates become temporarily negative. Our
non-Markovian quantum jump (NMQJ) approach circumvents this problem and
provides an efficient unravelling of the ensemble dynamics.Comment: 4 pages, 2 figures.V2: rewritten abstract and introduction, title
modified. V3: published version, new example case with photonic band ga
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