4,822 research outputs found
Quantum Zeno and anti-Zeno effects in the Friedrichs model
We analyze the short-time behavior of the survival probability in the frame
of the Friedrichs model for different formfactors. We have shown that this
probability is not necessary analytic at the time origin. The time when the
quantum Zeno effect could be observed is found to be much smaller than usually
estimated. We have also studied the anti-Zeno era and have estimated its
duration.Comment: References added. Appendix B shortened. Discussions extende
Spectroscopic studies of fractal aggregates of silver nanospheres undergoing local restructuring
We present an experimental spectroscopic study of large random colloidal
aggregates of silver nanoparticles undergoing local restructuring. We argue
that such well-known phenomena as strong fluctuation of local electromagnetic
fields, appearance of "hot spots" and enhancement of nonlinear optical
responses depend on the local structure on the scales of several nanosphere
diameters, rather that the large-scale fractal geometry of the sample.Comment: 3.5 pages, submitted to J. Chem. Phy
The first light of Mini-MegaTORTORA wide-field monitoring system
Here we describe the first light of the novel 9-channel wide-field optical
monitoring system with sub-second temporal resolution, Mini-MegaTORTORA, which
is being tested now at Special Astrophysical Observatory on Russian Caucasus.
The system is able to observe the sky simultaneously in either wide (~900
square degrees) or narrow (~100 square degrees) fields of view, either in clear
light or with any combination of color (Johnson B, V or R) polarimetric filters
installed, with exposure times ranging from 100 ms to 100 s. The primary goal
of the system is the detection of rapid -- with sub-second characteristic
time-scales -- optical transients, but it may be also used for studying the
variability of the sky objects on longer time scales.Comment: 9 pages, 9 figures, based on the talk presented on "Modern stellar
astronomy-2014" (Rostov-on-Don
Optical Camera with high temporal resolution to search for transients in the wide field
The wide field optical camera with high temporal resolution for the
continuous monitoring of the sky in order to catch the initial stages of GRBs
is described.Comment: 4 pages, 4 figures. To be published in "Il Nuovo Cimento",
Proceedings of the 4th Rome Workshop on Gamma-Ray Bursts in the Afterglow
Era, eds. L. Piro, L. Amati, S. Covino, B. Gendr
Entanglement may enhance the channel capacity in arbitrary dimensions
We consider explicitly two examples of d-dimensional quantum channels with
correlated noise and show that, in agreement with previous results on Pauli
qubit channels, there are situations where maximally entangled input states
achieve higher values of the output mutual information than product states. We
obtain a strong dependence of this effect on the nature of the noise
correlations as well as on the parity of the space dimension, and conjecture
that when entanglement gives an advantage in terms of mutual information,
maximally entangled states achieve the channel capacity.Comment: 12 pages, 3 figure
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