Proposal for an optical laser producing light at half the Josephson frequency

We describe a superconducting device capable of producing laser light in the visible range at half of the Josephson generation frequency with the optical phase of the light locked to the superconducting phase difference. It consists of two single-level quantum dots embedded into a p-n semiconducting heterostructure and surrounded by a cavity supporting a resonant optical mode. We study decoherence and spontaneous switching in the device.Comment: 4+3 pages, 3+1 figure

Motivasi Rusia Menganeksasi Semenanjung Krimea Tahun 2014

This research describes Russias motivation on taking Crimea Peninsula byforce from Ukraine in March 2014 or internationally called as CrimeaAnnexation. After Ukraines Euromaidan Revolution ended in february 2014with the escape of President Viktor Yanukovych to Russia and the interimgovernment was formed, a new separatist conflict arise in the regions thatpredominantly Russian speakers and led by the Crimea secession which wasfollowed soon by Russias annexation. Russia has been violated manyinternational agreements and bring it to the condemnation by internationalcommunity and western countries were planned to impose sanctions. Thiscase will be analyzed within the framework of offensive realism with securityapproach. Under the assumptions of the thories, security dilemma andoffensive capabilities lead to the expansion by great powers, mainly territorialexpansion. Russia seeking to strengthening political influence and security inthe Black Sea Region, where Crimea, Ukraine, and Russia are located.Security dilemma comes from political and military expansion by NATO,European Union, and United States. Annexation of Crimea showed thatRussia has returned to a great power and the rivalry between Westerncountries and Russia actually continues even though cold war has ended morethan two decades ago.Keywords: Annexation, Black Sea Region, European Union, Territorial Expansion,NATO, Offensive Realism, Russia, Securit

Evolution of a localized electron spin in a nuclear spin environment

Motivated by recent interest in the role of the hyperfine interaction in quantum dots we study the dynamics of a localized electron spin coupled to many nuclei. An important feature of the model is that the coupling to an individual nuclear spin depends on its position in the quantum dot. We introduce a semi-classical description of the system valid in the limit of a large number of nuclei and analyze the resulting classical dynamics. Contrary to a natural assumption, the correlation functions of electron spin with an arbitrary initial condition show no decay in time. Rather, they exhibit complicated undamped oscillations. This may be attributed to the fact that the system has many integrals of motion and is close to an integrable one. The ensemble averaged correlation functions do exhibit a slow decay (1/ln(t)) for t -> \infty.Comment: 11 pages, 11 figures, revtex4 styl

Full Counting Statistics of Non-Commuting Variables: the Case of Spin Counts

We discuss the Full Counting Statistics of non-commuting variables with the measurement of successive spin counts in non-collinear directions taken as an example. We show that owing to an irreducible detector back-action, the FCS in this case may be sensitive to the dynamics of the detectors, and may differ from the predictions obtained with using a naive version of the Projection Postulate. We present here a general model of detector dynamics and path-integral approach to the evaluation of FCS. We concentrate further on a simple "diffusive" model of the detector dynamics where the FCS can be evaluated with transfer-matrix method. The resulting probability distribution of spin counts is characterized by anomalously large higher cumulants and substantially deviates from Gaussian Statistics.Comment: 11 pages, 3 figure

Time dependent impurity in ultracold fermions: orthogonality catastrophe and beyond

Recent experimental realization of strongly imbalanced mixtures of ultracold atoms opens new possibilities for studying impurity dynamics in a controlled setting. We discuss how the techniques of atomic physics can be used to explore new regimes and manifestations of Anderson's orthogonality catastrophe (OC), which could not be accessed in solid state systems. We consider a system of impurity atoms localized by a strong optical lattice potential and immersed in a sea of itinerant Fermi atoms. Ramsey interference experiments with impurity atoms probe OC in the time domain, while radio-frequency (RF) spectroscopy probes OC in the frequency domain. The OC in such systems is universal for all times and is determined by the impurity scattering length and Fermi wave vector of itinerant fermions. We calculate the universal Ramsey response and RF absorption spectra. In addition to the standard power-law contribution, which corresponds to the excitation of multiple particle-hole pairs near the Fermi surface, we identify a novel contribution to OC that comes from exciting one extra particle from the bottom of the itinerant band. This gives rise to a non-analytic feature in the RF absorption spectra, which evolves into a true power-law singularity with universal exponent 1/4 at the unitarity. Furthermore, we discuss the manifestations of OC in spin-echo experiments, as well as in the energy counting statistic of the Fermi gas following a sudden quench of the impurity state. Finally, systems in which the itinerant fermions have two or more hyperfine states provide an even richer playground for studying non-equilibrium impurity physics, allowing one to explore non-equilibrium OC and to simulate quantum transport through nano-structures. This provides a useful connection between cold atomic systems and mesoscopic quantum transport.Comment: 15 pages, 7 figure

Effect of different 1-methylcyclopropene doses on the postharvest period of pitahaya fruits (Selenicereus megalanthus Haw.)

Colombia is one of the leading producers of yellow dragon fruit, but exports of this fruit is low when compared to the domestic production because most do not meet the requirements of international markets in terms of quality and preservation. As a result, this study aimed to determine the effect of theapplication of 1-methylcyclopropene (1-MCP) on the preservation and quality of dragon fruit, given that it has been effective in the conservation and postharvest quality of many agricultural species allowing longer life, using a completely randomized experiment design with three treatments: 0, 300 and 600 mg L-1 of 1-MCP, with four replications. The 600 mg L-1 of 1-MCP dose was able to maintain the quality of the dragon fruit longer (28 days after harvest (dah)) because it managed to reduce the respiratory rate. The application of 1-MCP did not affect the firmness, loss of mass, total soluble solids, total titratable acidity, or total carotenoids in the fruits. The application of 1-MCP slowed the loss of fruit quality in terms of color because the 600 mg L-1 dose maintained the lightness of the fruits longer, reduced the color changes as expressed in a* and b* values and decreased the chlorophyll degradation