3,105 research outputs found
Biochemical genetics of brown trout (salmo trutta L.): Isozyme variation as an indication of natural population structures and genetic variation in brown trout
Adiabatic two-qubit gates in capacitively coupled quantum dot hybrid qubits
The ability to tune qubits to flat points in their energy dispersions ("sweet
spots") is an important tool for mitigating the effects of charge noise and
dephasing in solid-state devices. However, the number of derivatives that must
be simultaneously set to zero grows exponentially with the number of coupled
qubits, making the task untenable for as few as two qubits. This is a
particular problem for adiabatic gates, due to their slower speeds. Here, we
propose an adiabatic two-qubit gate for quantum dot hybrid qubits, based on the
tunable, electrostatic coupling between distinct charge configurations. We
confirm the absence of a conventional sweet spot, but show that controlled-Z
(CZ) gates can nonetheless be optimized to have fidelities of 99% for a
typical level of quasistatic charge noise (1
eV). We then develop the concept of a dynamical sweet spot (DSS), for
which the time-averaged energy derivatives are set to zero, and identify a
simple pulse sequence that achieves an approximate DSS for a CZ gate, with a
5 improvement in the fidelity. We observe that the results depend on
the number of tunable parameters in the pulse sequence, and speculate that a
more elaborate sequence could potentially attain a true DSS.Comment: 14 pages, 9 figure
Using Land Evaluation and Site Assessment (LESA) for Farmland Protection Planning: A Case Study
The Land Evaluation and Site Assessment (LESA) system was used in developing a farmland protection plan that identified and described land use variables and agricultural operations associated with development. Using automated property tax data, a baseline model was established that identified field crops, vacant lands, truck cropland, and population as variables positively associated with development, whereas fruit crops had a negative association. Variables associated with development were lowest in profit per acre, whereas fruit crops were higher in profit. LESA and the model provided an objective and innovative approach to identify and recommend agricultural lands for farmland protection planning and implementation efforts
Akt1 and -2 inhibition diminishes terminal differentiation and enhances central memory CD8(+) T-cell proliferation and survival
The authors thank Dr Esteban Celis and Dr Rhea-Beth Markowitz for reviewing the manuscript and for their valuable suggestions and also thank Dr Lei Huang for his suggestions.Peer reviewedPublisher PD
Cooling of cryogenic electron bilayers via the Coulomb interaction
Heat dissipation in current-carrying cryogenic nanostructures is problematic
because the phonon density of states decreases strongly as energy decreases. We
show that the Coulomb interaction can prove a valuable resource for carrier
cooling via coupling to a nearby, cold electron reservoir. Specifically, we
consider the geometry of an electron bilayer in a silicon-based
heterostructure, and analyze the power transfer. We show that across a range of
temperatures, separations, and sheet densities, the electron-electron
interaction dominates the phonon heat-dissipation modes as the main cooling
mechanism. Coulomb cooling is most effective at low densities, when phonon
cooling is least effective in silicon, making it especially relevant for
experiments attempting to perform coherent manipulations of single spins.Comment: 9 pages, 5 figure
Phonon dispersion and phonon densities of states for ZnS and ZnTe
Neutron scattering data are reported for IIāVI zincblende crystals, which are believed to be of sufficient precision to refine earlier ZnS ambiguities and to provide a basis for model fitting comparable to existing IIIāV results. Valence shell models, including 9ā12 parameters (VSM) and a variable shell charge extension (VCM), were fit to the data and used to generate phonon density of states and Debye temperatures. Very good fits to the neutron data were obtained, but no model was found that also predicts an accurate set of electric and mechanical constants. It is concluded that an unambiguous ionic charge Z cannot be assigned from the neutron results in either case.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71346/2/JCPSA6-60-9-3613-1.pd
- ā¦