471 research outputs found
Linear optics implementation of weak values in Hardy's paradox
We propose an experimental setup for the implementation of weak measurements
in the context of the gedankenexperiment known as Hardy's Paradox. As Aharonov
et al. showed, these weak values form a language with which the paradox can be
resolved. Our analysis shows that this language is indeed consistent and
experimentally testable. It also reveals exactly how a combination of weak
values can give rise to an apparently paradoxical result.Comment: 4 pages, accepted by PR
Reply to "Comment on 'A linear optics implementation of weak values in Hardy's paradox'"
The comment by Lundeen et al. contains two criticisms of our proposal. While
we agree that the state-preparation procedure could be replaced by a simpler
setup as proposed by the authors of the comment, we do not agree with the
authors on their second, and more important point regarding two-particle weak
measurements. We believe this to be the result of a misunderstanding of our
original paper.Comment: 2 pages, accepted in PR
Weak Measurement of the Arrival Times of Single Photons and Pairs of Entangled Photons
In this paper we propose a setup for the weak measurement of photon arrival
time. It is found that the weak values of this arrival time can lie far away
from the expectation value, and in principle also in regions forbidden by
special relativity. We discuss in brief the implications of these results as
well as their reconciliation with the principle of causality. Furthermore, an
analysis of the weak arrival times of a pair of photons in a Bell state shows
that these weak arrival times are correlated.Comment: 4 pages, 1 figur
General implementation of all possible positive-operator-value measurements of single photon polarization states
Positive Operator Value Measures (POVMs) are the most general class of
quantum measurements. We propose a setup in which all possible POVMs of a
single photon polarization state (corresponding to all possible sets of
two-dimensional Kraus operators) can be implemented easily using linear optics
elements. This method makes it possible to experimentally realize any
projective orthogonal, projective non-orthogonal or non-projective sets of any
number of POVM operators. Furthermore our implementation only requires vacuum
ancillas, and is deterministic rather than probabilistic. Thus it realizes
every POVM with the correct set of output states. We give the settings required
to implement two different well-known non-orthogonal projective POVMs.Comment: 5 pages, newer version with minor addition
Introduction of Macromolecules into Bovine Adrenal Medullary Chromaffin Cells and Rat Pheochromocytoma Cells (PC12) by Permeabilization with Streptolysin O: Inhibitory Effect of Tetanus Toxin on Catecholamine Secretion
Conditions are described for controlled plasma membrane permeabilization of rat pheochromocytoma cells (PC12) and cultured bovine adrenal chromaffin cells by Streptolysin O (SLO). The transmembrane pores created by SLO invoke rapid efflux of intracellular 86Rb+ and ATP, and also permit passive diffusion of proteins, including immunoglobulins, into the cells. SLO-permeabilized PC12 cells release [3H]dopamine in response to micromolar concentrations of free Ca2+. Permeabilized adrenal chromaffin cells present a similar exocytotic response to Ca2+ in the presence of Mg2+/ ATP. Permeabilized PC12 cells accumulate antibodies against synaptophysin and calmodulin, but neither antibody reduces the Ca2+-dependent secretory response. Reduced tetanus toxin, although ineffective when applied to intact chromaffin cells, inhibits Ca2+-induced exocytosis by both types of permeabilized cells studied. Omission of dithiothreitol, toxin inactivation by boiling, or preincubation with neutralizing antibodies abolishes the inhibitory effect. The data indicate that plasma membrane permeabilization by Streptolysin O is a useful tool to probe and define cellular components that are involved in the final steps of exocytosis
Further Characterization of Dopamine Release by Permeabilized PC 12 Cells
Rat pheochromocytoma cells (PC 12) permeabilized with staphylococcal α-toxin release [3H]dopamine after addition of micromolar Ca2+. This does not require additional Mg2+-ATP (in contrast to bovine adrenal medullary chromaffin cells). We also observed Ca2+-dependent [3H]-dopamine release from digitonin-permeabilized PC 12 cells. Permeabilization with α-toxin or digitonin and stimulation of the cells were done consecutively to wash out endogenous Mg2+-ATP. During permeabilization, ATP was removed effectively from the cytoplasm by both agents but the cells released [3H]dopamine in response to micromolar Ca2+ alone. Replacement by chloride of glutamate, which could sustain mitochondrial ATP production in permeabilized cells, does not significantly alter catecholamine release induced by Ca2+. However, Mg2+ without ATP augments the Ca2+-induced release. The release was unaltered by thiol-, hydroxyl-, or calmodulin-interfering substances. Thus Mg2+-ATP, calmodulin, or proteins containing -SH or -OH groups are not necessary for exocytosis in permeabilized PC 12 cells
Synchronization of Sound Sources
Sound generation and -interaction is highly complex, nonlinear and
self-organized. Already 150 years ago Lord Rayleigh raised the following
problem: Two nearby organ pipes of different fundamental frequencies sound
together almost inaudibly with identical pitch. This effect is now understood
qualitatively by modern synchronization theory (M. Abel et al., J. Acoust. Soc.
Am., 119(4), 2006). For a detailed, quantitative investigation, we substituted
one pipe by an electric speaker. We observe that even minute driving signals
force the pipe to synchronization, thus yielding three decades of
synchronization -- the largest range ever measured to our knowledge.
Furthermore, a mutual silencing of the pipe is found, which can be explained by
self-organized oscillations, of use for novel methods of noise abatement.
Finally, we develop a specific nonlinear reconstruction method which yields a
perfect quantitative match of experiment and theory.Comment: 5 pages, 4 figure
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