203 research outputs found
Photon assisted tunneling in pairs of silicon donors
Shallow donors in silicon are favorable candidates for the implementation of solid-state quantum computer architectures because of the promising combination of atomiclike coherence properties and scalability from the semiconductor manufacturing industry. Quantum processing schemes require (among other things) controlled information transfer for readout. Here we demonstrate controlled electron tunneling at 10 K from P to Sb impurities and vice versa with the assistance of resonant terahertz photons
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Competing Inversion-Based Lasing and Raman Lasing in Doped Silicon
We report on an optically pumped laser where photons are simultaneously generated by population inversion and by stimulated Raman scattering in the same active medium, namely crystalline silicon doped by bismuth (SiBi). The medium utilizes three electronic levels: ground state [|
Violation of a Leggett-Garg inequality with ideal non-invasive measurements
The quantum superposition principle states that an entity can exist in two
different states simultaneously, counter to our 'classical' intuition. Is it
possible to understand a given system's behaviour without such a concept? A
test designed by Leggett and Garg can rule out this possibility. The test,
originally intended for macroscopic objects, has been implemented in various
systems. However to-date no experiment has employed the 'ideal negative result'
measurements that are required for the most robust test. Here we introduce a
general protocol for these special measurements using an ancillary system which
acts as a local measuring device but which need not be perfectly prepared. We
report an experimental realisation using spin-bearing phosphorus impurities in
silicon. The results demonstrate the necessity of a non-classical picture for
this class of microscopic system. Our procedure can be applied to systems of
any size, whether individually controlled or in a spatial ensemble.Comment: 6+4 pages. Supplementary Methods section include
Photon Filamentation in Resonant Media with High Fresnel Numbers
The phenomenon of turbulent photon filamentation occurs in lasers and other
active optical media at high Fresnel numbers. A description of this phenomenon
is suggested. The solutions to evolution equations are presented in the form of
a bunch of filaments chaotically distributed in space and having different
radii. The probability distribution of patterns is defined characterizing the
probabilistic weight of different filaments. The most probable filament radius
and filament number are found, being in good agreement with experiment.Comment: Revtex file, 5 pages. Reference to the English edition of the journal
is give
Radial distribution of a single-pass amplified radiation in the active elements of CuBr lasers
The paper presents the results of study of single-pass amplified radiation distribution of copper bromide vapor laser active elements used in high-speed laser monitors. The possibility of modifying the profile of a single-pass amplified light beam by changing the copper bromide vapor concentration is demonstrated. This means of influence on the radiation profile seems to be easiest due to implementation by varying only one parameter of operation. Gaussian, ring-shaped or flat profiles can be achieved depending on the temperature of the containers with copper bromide. The diameter of the beam becomes narrower when increasing the concentration of copper bromide vapor. This feature is characteristic of the discharge tubes as small (diameter 2.5, length 5 cm) and large (diameter 5 cm, length 90 cm) active volume
New method of studying slow strange meson properties in nuclear matter
We suggest the new experimental method to explore the properties of slow
strange mesons at normal nuclear matter density. We show that the and
mesons with extremely small momenta relative to the surrounding medium
rest frame can be produced in nucleus-nucleon collisions and their production
cross sections are experimentally measurable. The experiments on study of the
momentum dependence of meson-nuclear potentials are discussed.Comment: 4 pages, 2 figure
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