534 research outputs found
Cytoplasmic Ca2+ oscillations evoked by acetylcholine or intracellular infusion of inositol trisphosphate or Ca2+ can be inhibited by internal Ca2+
AbstractIn single internally perfused mouse pancreatic acinar cells, changes in the free intracellular Ca2+ concentration ([Ca2+]i) were monitored by measuring the Ca2+-dependent transmembrane Cl− current under voltage-clamp conditions. Cytoplasmic Ca2+ oscillations were induced by external acetylcholine (ACh) application, internal infusion of inositol (1,4,5) trisphosphate or its non-metabolizable analogue inositol trisphosphorothioate or by intracellular Ca2+ infusion. Such [Ca2+]i oscillations could be rapidly inhibited by external application of the Ca2+ ionophore ionomycin (10–100 nM). Cytoplasmic Ca2+ oscillations could also be evoked by external caffeine (1 mM) application when the internal perfusion solution did not contain any Ca2+ chelator. In such cases intracellular Ca2+ infusion transiently abolished the [Ca2+]i oscillations. We conclude that although Ca2+-induced Ca2+ release is the cause of the ACh-evoked [Ca2+]i oscillations, there is also a negative feed-back since Ca2+ can inhibit Ca2+ release initiated by Ca2+
Experimental verification of a fully inseparable tripartite continuous-variable state
A continuous-variable tripartite entangled state is experimentally generated
by combining three independent squeezed vacuum states and the variances of its
relative positions and total momentum are measured. We show that the measured
values violate the separability criteria based on the sum of these quantities
and prove the full inseparability of the generated state.Comment: 5 pages, 4 figure
All-optical generation of states for "Encoding a qubit in an oscillator"
Both discrete and continuous systems can be used to encode quantum
information. Most quantum computation schemes propose encoding qubits in
two-level systems, such as a two-level atom or an electron spin. Others exploit
the use of an infinite-dimensional system, such as a harmonic oscillator. In
"Encoding a qubit in an oscillator" [Phys. Rev. A 64 012310 (2001)], Gottesman,
Kitaev, and Preskill (GKP) combined these approaches when they proposed a
fault-tolerant quantum computation scheme in which a qubit is encoded in the
continuous position and momentum degrees of freedom of an oscillator. One
advantage of this scheme is that it can be performed by use of relatively
simple linear optical devices, squeezing, and homodyne detection. However, we
lack a practical method to prepare the initial GKP states. Here we propose the
generation of an approximate GKP state by using superpositions of optical
coherent states (sometimes called "Schr\"odinger cat states"), squeezing,
linear optical devices, and homodyne detection.Comment: 4 pages, 3 figures. Submitted to Optics Letter
Analyzing power for the proton elastic scattering from neutron-rich 6He nucleus
Vector analyzing power for the proton-6He elastic scattering at 71
MeV/nucleon has been measured for the first time, with a newly developed
polarized proton solid target working at low magnetic field of 0.09 T. The
results are found to be incompatible with a t-matrix folding model prediction.
Comparisons of the data with g-matrix folding analyses clearly show that the
vector analyzing power is sensitive to the nuclear structure model used in the
reaction analysis. The alpha-core distribution in 6He is suggested to be a
possible key to understand the nuclear structure sensitivity.Comment: 5 pages, 3 figures, accepted for publication as a Rapid Communication
in Physical Review
On the distillation and purification of phase-diffused squeezed states
Recently it was discovered that non-Gaussian decoherence processes, such as
phase-diffusion, can be counteracted by purification and distillation protocols
that are solely built on Gaussian operations. Here, we make use of this
experimentally highly accessible regime, and provide a detailed experimental
and theoretical analysis of several strategies for purification/distillation
protocols on phase-diffused squeezed states. Our results provide valuable
information for the optimization of such protocols with respect to the choice
of the trigger quadrature, the trigger threshold value and the probability of
generating a distilled state
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