6,659 research outputs found
Quantum engineering of atomic phase-shifts in optical clocks
Quantum engineering of time-separated Raman laser pulses in three-level
systems is presented to produce an ultra-narrow optical transition in bosonic
alkali-earth clocks free from light shifts and with a significantly reduced
sensitivity to laser parameter fluctuations. Based on a quantum artificial
complex-wave-function analytical model, and supported by a full density matrix
simulation including a possible residual effect of spontaneous emission from
the intermediate state, atomic phase-shifts associated to Ramsey and
Hyper-Ramsey two-photon spectroscopy in optical clocks are derived. Various
common-mode Raman frequency detunings are found where the frequency shifts from
off-resonant states are canceled, while strongly reducing their uncertainties
at the 10 level of accuracy.Comment: accepted for publication in PR
Severity of pediatric pain in relation to school-related functioning and teacher support: an epidemiological study among school-aged children and adolescents
Selective inhibitory effects of (S)-9-(3-hydroxy-2-phosphonyl-methoxypropyl)adenine and 1-(2'-deoxy-
From a selection of 25 antiviral compounds with specific anti-herpes activity or broad-spectrum antiviral properties, two compounds, namely (S)-9-(3-hydroxy-2-phosphonyl-methoxypropyl)adenine and 1-(2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl)-5-iodouracil, appeared particularly effective in inhibiting the cytopathogenicity of seal herpesvirus (phocid herpesvirus 1)
The Synthesis and Antiviral Properties of 8- Amino-3- [(2 hydroxyethoxy)methyl]-1,2,4-triazolo- [4,3-a ]pyrazine
The preparation of 8-amino-3-[(2-hydroxyethoxy)methyl]-1,2,4-
triazolo[4,3-a]pyrazine (IV) as an analogue of 9-[(2-hydroxyethoxy)
methyl]guanine and 9-(S)-(2,3-dihydroxypropyl)adenine is described
from the reaction of 3-chloro-2-hydrazinopyrazine (V) and ethyl 2-(2-acetoxyethoxy)thioacetimidate (IXg) followed by treatment with ammonia. Compound IV was found to lack antiviral properties towards herpes simplex I and II, vaccinia virus, vesicular stomatitis virus, measles, reovirus type 1, parainfluenza virus type 3, Sindbis virus, Coxsackie type B4 virus, and poliovirus type
Antimalarial chloroquine metamorphosed into antiviral agent against HIV with four modes of actions
Time-dependent Hamiltonian estimation for Doppler velocimetry of trapped ions
The time evolution of a closed quantum system is connected to its Hamiltonian
through Schroedinger's equation. The ability to estimate the Hamiltonian is
critical to our understanding of quantum systems, and allows optimization of
control. Though spectroscopic methods allow time-independent Hamiltonians to be
recovered, for time-dependent Hamiltonians this task is more challenging. Here,
using a single trapped ion, we experimentally demonstrate a method for
estimating a time-dependent Hamiltonian of a single qubit. The method involves
measuring the time evolution of the qubit in a fixed basis as a function of a
time-independent offset term added to the Hamiltonian. In our system the
initially unknown Hamiltonian arises from transporting an ion through a static,
near-resonant laser beam. Hamiltonian estimation allows us to estimate the
spatial dependence of the laser beam intensity and the ion's velocity as a
function of time. This work is of direct value in optimizing transport
operations and transport-based gates in scalable trapped ion quantum
information processing, while the estimation technique is general enough that
it can be applied to other quantum systems, aiding the pursuit of high
operational fidelities in quantum control.Comment: 10 pages, 8 figure
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