16,910 research outputs found
Quantum state transfer in imperfect artificial spin networks
High-fidelity quantum computation and quantum state transfer are possible in
short spin chains. We exploit a system based on a dispersive qubit-boson
interaction to mimic XY coupling. In this model, the usually assumed
nearest-neighbors coupling is no more valid: all the qubits are mutually
coupled. We analyze the performances of our model for quantum state transfer
showing how pre-engineered coupling rates allow for nearly optimal state
transfer. We address a setup of superconducting qubits coupled to a microstrip
cavity in which our analysis may be applied.Comment: 4 pages, 3 figures, RevTeX
A deeper insight into quantum state transfer from an information flux viewpoint
We use the recently introduced concept of information flux in a many-body
register in order to give an alternative viewpoint on quantum state transfer in
linear chains of many spins.Comment: 6 pages, 3 figures, RevTeX
Entanglement control in hybrid optomechanical systems
We demonstrate the control of entanglement in a hybrid optomechanical system
comprising an optical cavity with a mechanical end-mirror and an intracavity
Bose-Einstein condensate (BEC). Pulsed laser light (tuned within realistic
experimental conditions) is shown to induce an almost sixfold increase of the
atom-mirror entanglement and to be responsible for interesting dynamics between
such mesoscopic systems. In order to assess the advantages offered by the
proposed control technique, we compare the time-dependent dynamics of the
system under constant pumping with the evolution due to the modulated laser
light.Comment: Published versio
Geometric phase induced by a cyclically evolving squeezed vacuum reservoir
We propose a new way to generate an observable geometric phase by means of a
completely incoherent phenomenon. We show how to imprint a geometric phase to a
system by "adiabatically" manipulating the environment with which it interacts.
As a specific scheme we analyse a multilevel atom interacting with a broad-band
squeezed vacuum bosonic bath. As the squeezing parameters are smoothly changed
in time along a closed loop, the ground state of the system acquires a
geometric phase. We propose also a scheme to measure such geometric phase by
means of a suitable polarization detection.Comment: 4 pages, 1 figur
Entanglement production by quantum error correction in the presence of correlated environment
We analyze the effect of a quantum error correcting code on the entanglement
of encoded logical qubits in the presence of a dephasing interaction with a
correlated environment. Such correlated reservoir introduces entanglement
between physical qubits. We show that for short times the quantum error
correction interprets such entanglement as errors and suppresses it. However
for longer time, although quantum error correction is no longer able to correct
errors, it enhances the rate of entanglement production due to the interaction
with the environment.Comment: 7 pages, 3 figures, published versio
Effect of 1.5 MeV electron irradiation on the transmission of optical materials
Comparison of 1.5 MeV electron irradiation induced optical absorption of fused commercial silicas and optical transmission of Al2O3, MgF2, BaF2, LiF, and Be
Quantum synchronization as a local signature of super- and subradiance
We study the relationship between the collective phenomena of super and
subradiance and spontaneous synchronization of quantum systems. To this aim we
revisit the case of two detuned qubits interacting through a pure dissipative
bosonic environment, which contains the minimal ingredients for our analysis.
By using the Liouville formalism, we are able to find analytically the ultimate
connection between these phenomena. We find that dynamical synchronization is
due to the presence of long standing coherence between the ground state of the
system and the subradiant state. We finally show that, under pure dissipation,
the emergence of spontaneous synchronization and of subradiant emission occur
on the same time scale. This reciprocity is broken in the presence of dephasing
noise.Comment: 12 pages, 6 figure
Influence of a specific aquatic program on social and gross motor skills in adolescents with Autism Spectrum Disorders: Three case reports
Swimming pool activities revealed to be efficacious to train psychomotor skills and increase adaptive behaviors in children with Autism Spectrum Disorders (ASD). Therefore, the purpose of this study was to investigate the efficacy of a specific multi-systemic aquatic therapy (CI-MAT) on gross motor and social skills in three adolescents with Autism Spectrum Disorders (ASD). Methods: three adolescents with ASD of which two boys (M1 with a chronological age of 10.3 years and a mental age of 4.7 years; M2 with a chronological age of 14.6 and a mental age inferior to 4 years) and one girl (chronological age of 14.0 and a mental age inferior to 4 years). The study was divided into three phases: baseline, 12-week CI-MAT program and Post-Test. Participants were administered a battery of tests incorporating anthropometric measurements, gross motor development test and a social skills questionnaire before and after a 12-week MAT-CI program. Results: Subjects improved locomotors and object control skills following the CI-MAT program in a different way. Concerning social behaviors, the higher proportion of gains was observed in the sensitivity of other's presence and eye contact, for the contact domain, and in the comply turn for the relationship domain. Conclusions: The results of this study showed that the CI-MAT program was effective for the development of gross-motor skills and social behaviors in subjects with ASD. Moreover there is an urge to carry out a whole psychological assessment targeting both motor and adaptive development suitable to provide educational and vocational plans of exercises for people with ASD
Structural change in multipartite entanglement sharing: a random matrix approach
We study the typical entanglement properties of a system comprising two
independent qubit environments interacting via a shuttling ancilla. The initial
preparation of the environments is modeled using random-matrix techniques. The
entanglement measure used in our study is then averaged over many histories of
randomly prepared environmental states. Under a Heisenberg interaction model,
the average entanglement between the ancilla and one of the environments
remains constant, regardless of the preparation of the latter and the details
of the interaction. We also show that, upon suitable kinematic and dynamical
changes in the ancilla-environment subsystems, the entanglement-sharing
structure undergoes abrupt modifications associated with a change in the
multipartite entanglement class of the overall system's state. These results
are invariant with respect to the randomized initial state of the environments.Comment: 10 pages, RevTeX4 (Minor typo's corrected. Closer to published
version
Continuous production of KNO3 nanosalts for the fertilization of soil by means of a Spinning Disk Reactor
In this study the production of high soluble material
nanoparticles was successfully performed by means of a
spinning disk reactor (SDR). This result was possible due
to the use of a potassium nitrate saturated solution, which
was continuously recycled back to the reactor after
removal of the produced solid nanoparticles.
Several process configurations were checked. It appears to
be mandatory that the recycled saturated solution must be
free of residual nanoparticles since their presence would
lead to heterogeneous nucleation. In this respect, a small
amount of nitric acid was added to the stream to permit the
residual nanoparticle dissolution. Moreover, a spiral
wounded piping system was developed in order to increase
both the contact time and the mixing condition of the
saturated solution with the added acid before entering the
SD
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