1,474 research outputs found
The Connection Strategy: Preparing Young People to Succeed in College and Beyond
Describes the P-16 approach of linking education strategies from preschool through college graduation to better prepare low-income minority students. Discusses academic content, state policy strategies, and P-16 network efforts in Atlanta
Shot noise measurements in NS junctions and the semiclassical theory
We present a new analysis of shot noise measurements in normal
metal-superconductor (NS) junctions [X. Jehl et al., Nature 405, 50 (2000)],
based on a recent semiclassical theory. The first calculations at zero
temperature assuming quantum coherence predicted shot noise in NS contacts to
be doubled with respect to normal contacts. The semiclassical approach gives
the first opportunity to compare data and theory quantitatively at finite
voltage and temperature. The doubling of shot noise is predicted up to the
superconducting gap, as already observed, confirming that phase coherence is
not necessary. An excellent agreement is also found above the gap where the
noise follows the normal case.Comment: 2 pages, revtex, 2 eps figures, to appear in Phys. Rev.
Connecting Schools, Families, and Communities: Stories and Results from the Annie E. Casey Foundation's Education Investments
Provides an overview of the foundation's investment philosophy and its approach to defining and documenting grantmaking results. Highlights the work of seven school/family/community partnerships and the results they have achieved
Formal Verification of HotStuff
HotStuff is a recent algorithm for repeated distributed consensus used in permissioned blockchains. We present a simplified version of the HotStuff algorithm and verify its safety using both Ivy and the TLA Proof Systems tools.
We show that HotStuff deviates from the traditional view-instance model used in other consensus algorithms and instead follows a novel tree model to solve this fundamental problem. We argue that the tree model results in more complex verification tasks than the traditional view-instance model. Our verification efforts provide initial evidence towards this claim.acceptedVersio
Readout of relaxation rates by nonadiabatic pumping spectroscopy
We put forward nonadiabatic charge pumping as a method for accessing the
different charge relaxation rates as well as the relaxation rates of excited
orbital states in double-quantum-dot setups, based on extremely size-limited
quantum dots and dopant systems. The rates are obtained in a well-separated
manner from plateaus, occurring when comparing the steady-state current for
reversed driving cycles. This yields a reliable readout independent of any
fitting parameters. Importantly, the nonadiabatic pumping spectroscopy
essentially exploits the same driving scheme as the operation of these devices
generally employs. We provide a detailed analysis of the working principle of
the readout scheme as well as of possible errors, thereby demonstrating its
broad applicability. The precise knowledge of relaxation rates is highly
relevant for the implementation of time-dependently operated devices, such as
electron pumps for metrology or qubits in quantum information.Comment: 14 pages, 5 figure
Nonlocal effects in the shot noise of diffusive superconductor - normal-metal systems
A cross-shaped diffusive system with two superconducting and two normal
electrodes is considered. A voltage is applied between the normal
leads. Even in the absence of average current through the superconducting
electrodes their presence increases the shot noise at the normal electrodes and
doubles it in the case of a strong coupling to the superconductors. The
nonequilibrium noise at the superconducting electrodes remains finite even in
the case of a vanishingly small transport current due to the absence of energy
transfer into the superconductors. This noise is suppressed by
electron-electron scattering at sufficiently high voltages.Comment: 4 pages, RevTeX, 2 eps figure
A simple and controlled single electron transistor based on doping modulation in silicon nanowires
A simple and highly reproducible single electron transistor (SET) has been
fabricated using gated silicon nanowires. The structure is a
metal-oxide-semiconductor field-effect transistor made on silicon-on-insulator
thin films. The channel of the transistor is the Coulomb island at low
temperature. Two silicon nitride spacers deposited on each side of the gate
create a modulation of doping along the nanowire that creates tunnel barriers.
Such barriers are fixed and controlled, like in metallic SETs. The period of
the Coulomb oscillations is set by the gate capacitance of the transistor and
therefore controlled by lithography. The source and drain capacitances have
also been characterized. This design could be used to build more complex SET
devices.Comment: to be published in Applied Physics Letter
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