Quantum Computation and Spin Electronics

In this chapter we explore the connection between mesoscopic physics and quantum computing. After giving a bibliography providing a general introduction to the subject of quantum information processing, we review the various approaches that are being considered for the experimental implementation of quantum computing and quantum communication in atomic physics, quantum optics, nuclear magnetic resonance, superconductivity, and, especially, normal-electron solid state physics. We discuss five criteria for the realization of a quantum computer and consider the implications that these criteria have for quantum computation using the spin states of single-electron quantum dots. Finally, we consider the transport of quantum information via the motion of individual electrons in mesoscopic structures; specific transport and noise measurements in coupled quantum dot geometries for detecting and characterizing electron-state entanglement are analyzed.Comment: 28 pages RevTeX, 4 figures. To be published in "Quantum Mesoscopic Phenomena and Mesoscopic Devices in Microelectronics," eds. I. O. Kulik and R. Ellialtioglu (NATO Advanced Study Institute, Turkey, June 13-25, 1999

Counting statistics and detector properties of quantum point contacts

Quantum detector properties of the quantum point contact (QPC) are analyzed for arbitrary electron transparency and coupling strength to the measured system and are shown to be determined by the electron counting statistics. Conditions of the quantum-limited operation of the QPC detector which prevent information loss through the scattering time and scattering phases are found for arbitrary coupling. We show that the phase information can be restored and used for the quantum-limited detection by inclusion of the QPC detector in the electronic Mach-Zehnder interferometer.Comment: 4 pages, 2 figures, published versio

Young's modulus of polyelectrolyte multilayers from microcapsule swelling

We measure Young's modulus of a free polyelectrolyte multilayer film by studying osmotically induced swelling of polyelectrolyte multilayer microcapsules filled with the polyelectrolyte solution. Different filling techniques and core templates were used for the capsule preparation. Varying the concentration of the polyelectrolyte inside the capsule, its radius and the shell thickness yielded an estimate of an upper limit for Young's modulus of the order of 100 MPa. This corresponds to an elastomer and reflects strong interactions between polyanions and polycations in the multilayer

Soliton dynamics in deformable nonlinear lattices

We describe wave propagation and soliton localization in photonic lattices which are induced in a nonlinear medium by an optical interference pattern, taking into account the inherent lattice deformations at the soliton location. We obtain exact analytical solutions and identify the key factors defining soliton mobility, including the effects of gap merging and lattice imbalance, underlying the differences with discrete and gap solitons in conventional photonic structures.Comment: 5 pages, 4 figure

How to settle the Russian Ear East: Fate the Idea of the “Far Eastern Hectare”

The Far Eastern Federal District of Russia is the largest by area 40 6 of its territory but the most sparsely populated 5 57 of the population and economically inactive At the same time the number of residents of the District continues to decline The main reason for the observed quantitative losses is the outflow of the population in the form of the so-called Western migration drift The resulting demographic vacuum of the Far Eastern Federal district looks increasingly alarming against the background of very high demographic pressure on the adjacent territories of Russia s Asian neighbors The development of problematic territories always requires significant investments in human capital For sustainable development of the region and adequate realization of human capital it is necessary to create appropriate institutional conditions According to the decision of the Russian Government one of them is a mechanism for attracting labor resources to the Far East through the free provision of land plots called Far Eastern Hectare FE-hectare The article critically analyzes the implementation of this law The authors believe that high expectations from the project are associated not only with the unfavorable climate environment but also with the underdevelopment of transport infrastructure the lack of jobs low investment in human capital et

Dephasing in the electronic Mach-Zehnder interferometer at filling factor 2

We propose a simple physical model which describes dephasing in the electronic Mach-Zehnder interferometer at filling factor 2. This model explains very recent experimental results, such as the unusual lobe-type structure in the visibility of Aharonov-Bohm oscillations, phase rigidity, and the asymmetry of the visibility as a function of transparencies of quantum point contacts. According to our model, dephasing in the interferometer originates from strong Coulomb interaction at the edge of two-dimensional electron gas. The long-range character of the interaction leads to a separation of the spectrum of edge excitations on slow and fast mode. These modes are excited by electron tunneling and carry away the phase information. The new energy scale associated with the slow mode determines the temperature dependence of the visibility and the period of its oscillations as a function of voltage bias. Moreover, the variation of the lobe structure from one experiment to another is explained by specific charging effects, which are different in all experiments. We propose to use a strongly asymmetric Mach-Zehnder interferometer with one arm being much shorter than the other for the spectroscopy of quantum Hall edge states.Comment: 14 pages, 11 figure

Три новых чужеродных вида из семейства Chenopodiaceae во флоре России

Three new alien species of Chenopodiaceae s. str. (Amaranthaceae s. l.) are reported for the flora of Russia, the North American Chenopodiastrum simplex and Australian Dysphania carinata and D. pumilio. The identification of the specimens of Chenopodiastrum simplex from Moschny Island in the Leningrad Region (European Russia) was confirmed using both morphological and phylogenetic analyses. Morphologically, C. simplex is very similar to C. badachschanicum having the same fruit and seed characters. A single specimen of Dysphania carinata from Primorye Territory (the Russian Far East) was previously identified as Chenopodium pumilio (≡ Dysphania pumilio) incorrectly. Only recently, the latter species has been indeed found in Beslan town, Republic of North Ossetia - Alania (the North Caucasus). For each species, the possible degree of naturalization is discussed

Non-Hermitian trimers: PT-symmetry versus pseudo-Hermiticity

We study a structure composed of three coupled waveguides with gain and loss, a non-Hermitian trimer. We demonstrate that the mode spectrum can be entirely real if the waveguides are placed in a special order and at certain distances between each other. Such structures generally lack a spatial symmetry, in contrast to parity-time symmetric trimers which are known to feature a real spectrum. We also determine a threshold for wave amplification and analyse the scattering properties of such non-conservative systems embedded into a chain of conservative waveguides.SVS and AAS were supported by the Australian Research Council (ARC), Discovery Project DP160100619. SVS acknowledges financial support from the Russian Foundation for Basic Research, grant No.15-31-20037 mol_a

Design of Drum Type Apparatus for Processing of Bulk Materials

The article presents the development and research of drum continuous mixers, most attention is paid to the results of theoretical (using of cybernetic approach) and experimental studies of longitudinal mixing particulate material in rotating drums of continuous action, the influence of internal recycles of material flows, intensifying the process of smoothing the input fluctuations. The authors analyzed the influence of internal recycles material flows, intensifying the process of smoothing the input fluctuations. The results presented in this paper were obtained by the experiments on the smoothing ability determination during which they change the frequency of the drum rotation, the location of the Г-shaped mixer blades on the drum mixer. The article reported that the studies were conducted on three mixtures which components have different physical and mechanical systems with various dispersed liquid additives and without it

Electron shot noise beyond the second moment

The form of electron counting statistics of the tunneling current noise in a generic many-body interacting electron system is obtained. The third correlator of current fluctuations (the skewness of the charge counting distribution) has a universal relation with the current I and the quasiparticle charge q. This relation C_3 = q^2 I holds in a wide bias voltage range, both at large and small eV/kT, thereby representing an advantage compared to the Schottky formula. We consider the possibility of using the counting statistics for detecting quasiparticle charge at high temperature.Comment: 4 pages, 2 figure