34 research outputs found
Bell measurements as a witness of a dualism in entanglement
We show how a property of dualism, which can exist in the entanglement of
identical particles, can be tested in the usual photonic Bell measurement
apparatus with minor modifications. Two different sets of coincidence
measurements on the same experimental setup consisting of a Hong-Ou-Mandel
interferometer demonstrate how the same two-photon state can emerge
entanglement in the polarization or the momentum degree of freedom depending on
the dynamical variables used for labeling the particles. Our experiment
demonstrates how the same source can be used as both a polarization entangled
state, as well as a dichotomic momentum entangled state shared between distant
users Alice and Bob in accordance to which sets of detectors they access. When
the particles become distinguishable by letting the information about one of
the variables to be imprinted in yet another (possibly inaccessible) system or
degree of freedom, the feature of dualism is expected to vanish. We verify this
feature by polarization decoherence (polarization information in environment)
or arrival time difference, which both respectively destroy one of the dual
forms of entanglement.Comment: 5 pages, 4 figure
Native NIR-emitting single colour centres in CVD diamond
Single-photon sources are a fundamental element for developing quantum
technologies, and sources based on colour centres in diamonds are among the
most promising candidates. The well-known NV centres are characterized by
several limitations, thus few other defects have recently been considered. In
the present work, we characterize in detail native efficient single colour
centres emitting in the near infra-red in both standard IIa single-crystal and
electronic-grade polycrystalline commercial CVD diamond samples. In the former
case, a high-temperature annealing process in vacuum is necessary to induce the
formation/activation of luminescent centres with good emission properties,
while in the latter case the annealing process has marginal beneficial effects
on the number and performances of native centres in commercially available
samples. Although displaying significant variability in several photo physical
properties (emission wavelength, emission rate instabilities, saturation
behaviours), these centres generally display appealing photophysical properties
for applications as single photon sources: short lifetimes, high emission rates
and strongly polarized light. The native centres are tentatively attributed to
impurities incorporated in the diamond crystal during the CVD growth of
high-quality type IIa samples, and offer promising perspectives in
diamond-based photonics.Comment: 27 pages, 10 figures. Submitted to "New Journal of Phsyics",
NJP-100003.R
Clinical manifestation of radiation-exposed tuberculosis when uranium production
Present study was performed in Krasnokamensk city. We conducted retrospective study of 34 incident cases of tuberculosis (TB) among employees of the Priargunsky Industrial Mining and Chemical Union exposed to radiation (uranium production and processing). The comparison group included 47 TB patients, permanent residents of Krasnokamensk. The study found out that long-term dynamics of TB morbidity in the main group exceeded the one of the comparison group. Among the employees, most cases were registered in the 20-35 age group (47.0 %), and among the Krasnokamensk residents - in the 35-50 age group (51.0 %). In the main group, the most common cases were gross and extrapulmonary forms of tuberculosis (53.0 % and 14.7 % respectively). In the comparison group, minor TB forms dominated (59.5 %) and only one case of extrapulmonary tuberculosis was registered (p < 0.05). The effectiveness of the treatment in compared groups did not differ
Polarization ququarts
We discuss the concept of polarization states of four-dimensional quantum
systems based on frequency non-degenerate biphoton field. Several quantum
tomography protocols were developed and implemented for measurement of an
arbitrary state of ququart. A simple method that does not rely on
interferometric technique is used to generate and measure the sequence of
states that can be used for quantum communication purposes.Comment: 13 pages, 10 figure
Somatoform disorders in the family doctor's practice.
Somatoform disorders – psychogenic diseases are characterized by pathological physical symptoms that resemble somatic illness. Thus, any organic manifestations, which can be attributed to known diseases are not detected, but there are non-specific functional impairments. Somatoform disorders include somatization disorder, undifferentiated somatoform disorder, hypochondriacal disorder, somatoform dysfunction of the autonomic nervous system and stable somatoform pain disorder. The first part of the article reviewes features of the clinical manifestations of somatization disorder and undifferentiated somatoform disorder. Role of non-benzodiazepine tranquilizers (ADAPTOL) and metabolic drugs (VASONAT) in the treatment of patients with somatoform disorders is discussed. In review article data of neurologists and cardiologists on the effectiveness of anxiolytic drug ADAPTOL and metabolic drug VASONAT in different clinical groups of patients (coronary artery disease, chronic ischemia of the brain), which can significantly improve quality of life, increase exercise tolerance, improve cognitive function and correct mental and emotional disorders are presented
Nanodiamonds-induced effects on neuronal firing of mouse hippocampal microcircuits
Fluorescent nanodiamonds (FND) are carbon-based nanomaterials that can
efficiently incorporate optically active photoluminescent centers such as the
nitrogen-vacancy complex, thus making them promising candidates as optical
biolabels and drug-delivery agents. FNDs exhibit bright fluorescence without
photobleaching combined with high uptake rate and low cytotoxicity. Focusing on
FNDs interference with neuronal function, here we examined their effect on
cultured hippocampal neurons, monitoring the whole network development as well
as the electrophysiological properties of single neurons. We observed that FNDs
drastically decreased the frequency of inhibitory (from 1.81 Hz to 0.86 Hz) and
excitatory (from 1.61 Hz to 0.68 Hz) miniature postsynaptic currents, and
consistently reduced action potential (AP) firing frequency (by 36%), as
measured by microelectrode arrays. On the contrary, bursts synchronization was
preserved, as well as the amplitude of spontaneous inhibitory and excitatory
events. Current-clamp recordings revealed that the ratio of neurons responding
with AP trains of high-frequency (fast-spiking) versus neurons responding with
trains of low-frequency (slow-spiking) was unaltered, suggesting that FNDs
exerted a comparable action on neuronal subpopulations. At the single cell
level, rapid onset of the somatic AP ("kink") was drastically reduced in
FND-treated neurons, suggesting a reduced contribution of axonal and dendritic
components while preserving neuronal excitability.Comment: 34 pages, 9 figure
On Preparing Entangled Pairs of Polarization Qubits in the Frequency Non-Degenerate Regime
The problems associated with practical implementation of the scheme proposed
for preparation of arbitrary states of polarization ququarts based on biphotons
are discussed. The influence of frequency dispersion effects are considered,
and the necessity of group velocities dispersion compensation in the frequency
non-degenerate case even for continuous pumping is demonstrated. A method for
this compensation is proposed and implemented experimentally. Physical
restrictions on the quality of prepared two-photon states are revealed.Comment: 9 pages, 6 figure
Electroluminescence from a diamond device with ion-beam-micromachined buried graphitic electrodes
Focused MeV ion microbeams are suitable tools for the direct writing of
conductive graphitic channels buried in an insulating diamond bulk, as
demonstrated in previous works with the fabrication of multi-electrode ionizing
radiation detectors and cellular biosensors. In this work we investigate the
suitability of the fabrication method for the electrical excitation of colour
centres in diamond. Differently from photoluminescence, electroluminescence
requires an electrical current flowing through the diamond sub-gap states for
the excitation of the colour centres. With this purpose, buried graphitic
electrodes with a spacing of 10 micrometers were fabricated in the bulk of a
detector-grade CVD single-crystal diamond sample using a scanning 1.8 MeV He
micro-beam. The current flowing in the gap region between the electrodes upon
the application of a 250 V bias voltage was exploited as the excitation pump
for the electroluminescence of different types of colour centres localized in
the above-mentioned gap. The bright light emission was spatially mapped using a
confocal optical microscopy setup. The spectral analysis of electroluminescence
revealed the emission from neutrally-charged nitrogen-vacancy centres (,
= 575 nm), as well as from cluster crystal dislocations
(A-band, {\lambda} = 400-500 nm). Moreover, an electroluminescence signal with
appealing spectral features (sharp emission at room temperature, low phonon
sidebands) from He-related defects was detected ( = 536.3 nm,
= 560.5 nm); a low and broad peak around {\lambda} = 740 nm was
also observed and tentatively ascribed to Si-V or GR1 centres. These results
pose interesting future perspectives for the fabrication of
electrically-stimulated single-photon emitters in diamond for applications in
quantum optics and quantum cryptography