Phonon effects on the radiative recombination of excitons in double quantum dots

We study theoretically the radiative recombination of excitons in double quantum dots in the presence of carrier-phonon coupling. We show that the phonon-induced pure dephasing effects and transitions between the exciton states strongly modify the spontaneous emission process and make it sensitive to temperature, which may lead to non-monotonic temperature dependence of the time-resolved luminescence. We show also that under specific resonance conditions the biexcitonic interband polarization can be coherently transferred to the excitonic one, leading to an extended life time of the total coherent polarization, which is reflected in the nonlinear optical spectrum of the system. We study the stability of this effect against phonon-induced decoherence.Comment: 10 pages, 7 figure

Quantum dots as optimized chiral emitters for photonic integrated circuits

Chiral coupling, which allows directional interactions between quantum dots (QDs) and photonic crystal waveguide modes, holds promise for enhancing the functionality of quantum photonic integrated circuits. Elliptical polarizations of QD transitions offer a considerable enhancement in directionality. However, in epitaxial QD fabrication, the lack of precise control over lateral QD positions still poses a challenge in achieving efficient chiral interfaces. Here, we present a theoretical analysis in which we propose to optimize the polarization of a QD emitter against the spatially averaged directionality and demonstrate that the resulting emitter offers a considerable technological advantage in terms of the size and location of high-directionality areas of the waveguide as well as their overlap with the regions of large Purcell enhancement, thereby improving the scalability of the device. Moreover, using $\mathbf{\mathit{k}}\cdot\mathbf{\mathit{p}}$ modeling, we demonstrate that the optimal elliptical polarization can be achieved for neutral exciton transitions in a realistic QD structure. Our results present a viable path for efficient chiral coupling in QD-based photonic integrated circuits, to a large extent overcoming the challenges and limitations of the present manufacturing technology.Comment: Some text modifications in the Introduction, references added, typos corrected, Fig. 7 updated, and the title change

Population and labour in family farming in Poland

The socio-demographic characteristics of the farming population. Working life of persons living in agricultural holdings. Family labour inputs in family farms. Labour surplus and shortage. Hired labour and employment relationships in agriculture

Highly commercial farms in family farming in Poland

Highly commercial farms – overview. The distribution of highly commercial farms. Distribution of highly commercial farms according to social and demographic characteristics of farm managers. The distribution of highly commercial farms in size groups. Highly commercial farms in agricultural structures. Regional differences in the formation of the group of highly commercial Farms. Prospects of speeding up the development of highly commercial farms and strengthening their position in agriculture. The determinants of the economic potential of family farms. Support measures for increasing the economic potential of farms under the common agricultural policy. Intervention area of structural funds – measure 1.1: Investments in agricultural holdings

Changes in population and labour force in family farming in Poland

This paper discusses changes in population and labour in family farming in Poland. We analyse the size and socio-demographic characteristics of the farming population, the degree of utilisation of own labour resources on the farm and the assessment of labour inputs in family farming. Our research uses data from IERiGŻ-PIB field studies as well as general statistics. In comparison to the European Union as a whole, the socio-demographic (education and age) structure of the farming population in Poland is relatively favourable. There has been a signifi cant reduction in the share of persons working exclusively on the family farm while the share of those with off -farm employment has increased. Around 500,000 persons who are not registered as unemployed and may be considered as redundant from the point of view of farming activities and represent hidden unemployment. We conclude that employment on family farms has a decreasing role in reducing the imbalance in the rural labour market in Poland

Changes in social and economic development of small farms in Poland

The article discusses the progress of changes in the area structure of individual farms and related to this changes in the number of workers in agriculture as well as the issue of unused labour resources in Poland. The research material are public statistics data (Polish Statistical Office – GUS) and the results of own research carried out at IAFE-NRI. A detailed analysis of the decline in the share of people working in agriculture among the total number of employed in our country indicates that in the recent period the scale of decline in the value of this indicator is accelerating. These tendencies were mainly the result of a much larger than before increase in the number of non-agricultural workers, especially among rural residents