Single-electron latch with granular film charge leakage suppressor

A single-electron latch is a device that can be used as a building block for Quantum-dot Cellular Automata (QCA) circuits. It consists of three nanoscale metal "dots" connected in series by tunnel junctions; charging of the dots is controlled by three electrostatic gates. One very important feature of a single-electron latch is its ability to store ("latch") information represented by the location of a single electron within the three dots. To obtain latching, the undesired leakage of charge during the retention time must be suppressed. Previously, to achieve this goal, multiple tunnel junctions were used to connect the three dots. However, this method of charge leakage suppression requires an additional compensation of the background charges affecting each parasitic dot in the array of junctions. We report a single-electron latch where a granular metal film is used to fabricate the middle dot in the latch which concurrently acts as a charge leakage suppressor. This latch has no parasitic dots, therefore the background charge compensation procedure is greatly simplified. We discuss the origins of charge leakage suppression and possible applications of granular metal dots for various single-electron circuits.Comment: 21 pages, 4 figure

Age and growth of blue Antimora Antimora rostrata (Moridae) in Southwestern Greenland waters

The results of determination of age and study on growth of blue antimora Antimora rostrata from the waters of Southwestern Greenland are presented. The results are based on the analysis of 200 fish otoliths. In the catches, we found specimens of antimora with total lengths of 18−70 cm, body weights of 23−2731 g, at the age of 7−38 years. Minimal age of males (not considering juvenile individuals) was 10 years at body length of 27−33 cm; maximal age was 18 years at 42 cm. Minimal age of females was 9 years at length of 21–27 cm; maximal age was 38 years at 70 cm. The rate of linear growth in blue antimora from Southwestern Greenland waters is comparable to that in the fish from New Zealand and Ross Sea waters but considerably lower than indicated earlier for fish from the waters of Iceland, Greenland, and the Mid-Atlantic Ridge. The age of reaching sexual maturity in males and females is preliminary determined as 15 and 19−20 years, respectively

Growth and age of the roughhead grenadier Macrourus berglax in waters off Southwest Greenland

Data on the age and growth of the roughhead grenadier Macrourus berglax from waters off Southwest Greenland have been obtained based on the analysis of otoliths. Specimens with a preanal length of 5−39 cm, a weight of 7−5275 g, and age from 2 to 22 years are recorded in trawl catches. Roughhead grenadier exhibits a similar rate of linear growth in waters off Southwest Greenland and other parts of the range in the Northwest Atlantic. No considerable differences from the rate of the linear growth calculated earlier from scales for the species in waters off West Greenland have been found. In the recent period, the rate of weight gain in roughhead grenadier in waters off Southwest Greenland has been lower than in the Northwest Atlantic in the first half of the 1980s. The age of mass maturation in males (7–9 years) and females (16–17 years) in waters off West and East Greenland is somewhat higher than in coastal waters of Norway and the Northwest Atlantic

Semiorthogonal decompositions of derived categories of equivariant coherent sheaves

Let X be an algebraic variety with an action of an algebraic group G. Suppose X has a full exceptional collection of sheaves, and these sheaves are invariant under the action of the group. We construct a semiorthogonal decomposition of bounded derived category of G-equivariant coherent sheaves on X into components, equivalent to derived categories of twisted representations of the group. If the group is finite or reductive over the algebraically closed field of zero characteristic, this gives a full exceptional collection in the derived equivariant category. We apply our results to particular varieties such as projective spaces, quadrics, Grassmanians and Del Pezzo surfaces.Comment: 28 pages, uses XY-pi

Growth and age of the roughhead grenadier Macrourus berglax in waters off Southwest Greenland

Data on the age and growth of the roughhead grenadier Macrourus berglax from waters off Southwest Greenland have been obtained based on the analysis of otoliths. Specimens with a preanal length of 5−39 cm, a weight of 7−5275 g, and age from 2 to 22 years are recorded in trawl catches. Roughhead grenadier exhibits a similar rate of linear growth in waters off Southwest Greenland and other parts of the range in the Northwest Atlantic. No considerable differences from the rate of the linear growth calculated earlier from scales for the species in waters off West Greenland have been found. In the recent period, the rate of weight gain in roughhead grenadier in waters off Southwest Greenland has been lower than in the Northwest Atlantic in the first half of the 1980s. The age of mass maturation in males (7–9 years) and females (16–17 years) in waters off West and East Greenland is somewhat higher than in coastal waters of Norway and the Northwest Atlantic

Age and growth of blue Antimora Antimora rostrata (Moridae) in Southwestern Greenland waters

The results of determination of age and study on growth of blue antimora Antimora rostrata from the waters of Southwestern Greenland are presented. The results are based on the analysis of 200 fish otoliths. In the catches, we found specimens of antimora with total lengths of 18−70 cm, body weights of 23−2731 g, at the age of 7−38 years. Minimal age of males (not considering juvenile individuals) was 10 years at body length of 27−33 cm; maximal age was 18 years at 42 cm. Minimal age of females was 9 years at length of 21–27 cm; maximal age was 38 years at 70 cm. The rate of linear growth in blue antimora from Southwestern Greenland waters is comparable to that in the fish from New Zealand and Ross Sea waters but considerably lower than indicated earlier for fish from the waters of Iceland, Greenland, and the Mid-Atlantic Ridge. The age of reaching sexual maturity in males and females is preliminary determined as 15 and 19−20 years, respectively

Nano-photoluminescence of natural anyon molecules and topological quantum computation

International audienceThe proposal of fault-tolerant quantum computations, which promise to dramatically improve the operation of quantum computers and to accelerate the development of the compact hardware for them, is based on topological quantum field theories, which rely on the existence in Nature of physical systems described by a Lagrangian containing a non-Abelian (NA) topological term. These are solid-state systems having two-dimensional electrons, which are coupled to magnetic-flux-quanta vortexes, forming complex particles, known as anyons. Topological quantum computing (TQC) operations thus represent a physical realization of the mathematical operations involving NA representations of a braid group B$_{n}$, generated by a set of n localized anyons, which can be braided and fused using a “tweezer” and controlled by a detector. For most of the potential TQC material systems known so far, which are 2D-electron–gas semiconductor structure at high magnetic field and a variety of hybrid superconductor/topological-material heterostructures, the realization of anyon localization versus tweezing and detecting meets serious obstacles, chief among which are the necessity of using current control, i.e., mobile particles, of the TQC operations and high density electron puddles (containing thousands of electrons) to generate a single vortex. Here we demonstrate a novel system, in which these obstacles can be overcome, and in which vortexes are generated by a single electron. This is a ~ 150 nm size many electron InP/GaInP$_{2}$ self-organized quantum dot, in which molecules, consisting of a few localized anyons, are naturally formed and exist at zero external magnetic field. We used high-spatial-resolution scanning magneto-photoluminescence spectroscopy measurements of a set of the dots having five and six electrons, together with many-body quantum mechanical calculations to demonstrate spontaneous formation of the anyon magneto-electron particles (e$^{ν}$) having fractional charge ν = n/k, where n = 1–4 and k = 3–15 are the number of electrons and vortexes, respectively, arranged in molecular structures having a built-in (internal) magnetic field of 6–12 T. Using direct imaging of the molecular configurations we observed fusion and braiding of e$^{ν}$-anyons under photo-excitation and revealed the possibility of using charge sensing for their control. Our investigations show that InP/GaInP$_{2}$ anyon-molecule QDs, which have intrinsic transformations of localized e$^{ν}$-anyons compatible with TQC operations and capable of being probed by charge sensing, are very promising for the realization of TQC