1,218 research outputs found
Universal first-passage statistics of aging processes
Many out of equilibrium phenomena, such as diffusion-limited reactions or
target search processes, are controlled by first-passage events. So far the
general determination of the mean first-passage time (FPT) to a target in
confinement has left aside aging processes, involved in contexts as varied as
glassy dynamics, tracer diffusion in biological membranes or transport of cold
atoms in optical lattices. Here we consider general non-Markovian
scale-invariant processes in arbitrary dimension, displaying aging, and
demonstrate that all the moments of the FPT obey universal scalings with the
confining volume with non trivial exponents. Our analysis shows that a
nonlinear scaling of the mean FPT with the volume is the hallmark of aging and
provides a general tool to quantify its impact on first-passage kinetics in
confinement
Adiabatic creation of entangled states by a bichromatic field designed from the topology of the dressed eigenenergies
Preparation of entangled pairs of coupled two-state systems driven by a
bichromatic external field is studied. We use a system of two coupled spin-1/2
that can be translated into a three-state ladder model whose intermediate state
represents the entangled state. We show that this entangled state can be
prepared in a robust way with appropriate fields. Their frequencies and
envelopes are derived from the topological properties of the model.Comment: 10 pages, 9 figure
Adiabatic Evolution for Systems with Infinitely many Eigenvalue Crossings
We formulate an adiabatic theorem adapted to models that present an
instantaneous eigenvalue experiencing an infinite number of crossings with the
rest of the spectrum. We give an upper bound on the leading correction terms
with respect to the adiabatic limit. The result requires only differentiability
of the considered spectral projector, and some geometric hypothesis on the
local behaviour of the eigenvalues at the crossings
On the topology of adiabatic passage
We examine the topology of eigenenergy surfaces characterizing the population
transfer processes based on adiabatic passage. We show that this topology is
the essential feature for the analysis of the population transfers and the
prediction of its final result. We reinterpret diverse known processes, such as
stimulated Raman adiabatic passage (STIRAP), frequency-chirped adiabatic
passage and Stark-chirped rapid adiabatic passage (SCRAP). Moreover, using this
picture, we display new related possibilities of transfer. In particular, we
show that we can selectively control the level which will be populated in
STIRAP process in Lambda or V systems by the choice of the peak amplitudes or
the pulse sequence
Atom-photon, atom-atom and photon-photon entanglement preparation via fractional adiabatic passage
We propose a relatively robust scheme to generate maximally entangled states
of (i) an atom and a cavity photon, (ii) two atoms in their ground states, and
(iii) two photons in two spatially separate high-Q cavities. It is based on the
interaction via fractional adiabatic passage of a three-level atom traveling
through a cavity mode and a laser beam. The presence of optical phases is
emphasized.Comment: 6 pages, 7 figures. We have changed the title, the abstract and the
text. The references have been updated. (Accepted by Phys. Rev. A
Phase Transition in a One-Dimensional Extended Peierls-Hubbard Model with a Pulse of Oscillating Electric Field: III. Interference Caused by a Double Pulse
In order to study consequences of the differences between the
ionic-to-neutral and neutral-to-ionic transitions in the one-dimensional
extended Peierls-Hubbard model with alternating potentials for the TTF-CA
complex, we introduce a double pulse of oscillating electric field in the
time-dependent Schr\"odinger equation and vary the interval between the two
pulses as well as their strengths. When the dimerized ionic phase is
photoexcited, the interference effect is clearly observed owing to the
coherence of charge density and lattice displacements. Namely, the two pulses
constructively interfere with each other if the interval is a multiple of the
period of the optical lattice vibration, while they destructively interfere if
the interval is a half-odd integer times the period, in the processes toward
the neutral phase. The interference is strong especially when the pulse is
strong and short because the coherence is also strong. Meanwhile, when the
neutral phase is photoexcited, the interference effect is almost invisible or
weakly observed when the pulse is weak. The photoinduced lattice oscillations
are incoherent due to random phases. The strength of the interference caused by
a double pulse is a key quantity to distinguish the two transitions and to
evaluate the coherence of charge density and lattice displacements.Comment: 16 pages, 8 figure
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