1,979 research outputs found
Adiabatic quantum search with atoms in a cavity driven by lasers
We propose an implementation of the quantum search algorithm of a marked item
in an unsorted list of N items by adiabatic passage in a cavity-laser-atom
system. We use an ensemble of N identical three-level atoms trapped in a
single-mode cavity and driven by two lasers. In each atom, the same level
represents a database entry. One of the atoms is marked by having an energy gap
between its two ground states. Appropriate time delays between the two laser
pulses allow one to populate the marked state starting from an initial
entangled state within a decoherence-free adiabatic subspace. The time to
achieve such a process is shown to exhibit the Grover speedup.Comment: 5 pages, 3 figure
Quantum search by parallel eigenvalue adiabatic passage
We propose a strategy to achieve the Grover search algorithm by adiabatic
passage in a very efficient way. An adiabatic process can be characterized by
the instantaneous eigenvalues of the pertaining Hamiltonian, some of which form
a gap. The key to the efficiency is based on the use of parallel eigenvalues.
This allows us to obtain non-adiabatic losses which are exponentially small,
independently of the number of items in the database in which the search is
performed.Comment: 7 pages, 4 figure
Quantum state engineering in a cavity by Stark chirped rapid adiabatic passage
We propose a robust scheme to generate single-photon Fock states and
atom-photon and atom-atom entanglement in atom-cavity systems. We also present
a scheme for quantum networking between two cavity nodes using an atomic
channel. The mechanism is based on Stark-chirped rapid adiabatic passage
(SCRAP) and half-SCRAP processes in a microwave cavity. The engineering of
these states depends on the design of the adiabatic dynamics through the static
and dynamic Stark shifts.Comment: 7 pages, 8 figures, to be appeared in PL
Fast SWAP gate by adiabatic passage
We present a process for the construction of a SWAP gate which does not
require a composition of elementary gates from a universal set. We propose to
employ direct techniques adapted to the preparation of this specific gate. The
mechanism, based on adiabatic passage, constitutes a decoherence-free method in
the sense that spontaneous emission and cavity damping are avoided.Comment: 5 pages, 4 figures, submitted to Phys. Re
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
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
Adiabatic tracking for photo- and magneto-association of Bose-Einstein condensates with Kerr nonlinearities
We develop the method of adiabatic tracking for photo- and
magneto-association of Bose-Einstein atomic condensates with models that
include Kerr type nonlinearities. We show that the inclusion of these terms can
produce qualitatively important modifications in the adiabatic dynamics, like
the appearance of bifurcations, in which the trajectory that is being tracked
loses its stability. As a consequence the adiabatic theorem does not apply and
the adiabatic transfer can be strongly degraded. This degradation can be
compensated by using fields that are strong enough compared with the values of
the Kerr terms. The main result is that, despite these potentially detrimental
features, there is always a choice of the detuning that leads to an efficient
adiabatic tracking, even for relatively weak fields
Bayesian parameter estimation with prior weighting in ALT model
This paper provides an overview of the application of Bayesian inference to accelerated life testing (ALT) models for the concrete case of estimation by Maximum of Aposteriori (MAP) method in the case of constant stress levels. It studies the Bayesian inference over the accelerated life model as presented in [1]. It suites, integrates and generalizes the particular cases presented in [2] and [3]. Towards the end, weighting of the prior information according to data is integrated. The paper also illustrates an experimental example
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
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