179 research outputs found
The Significance of Baptism for the Christian\u27s Faith and Life
The very fact that Christ instituted and commanded Christian baptism is already enough to make it necessary. However, Jesus never instituted anything just for the sake of instituting, nor did the Master command for the sake of commanding. Baptism was given for the benefit of sinners. It is our purpose in the following pages to show the significance of baptism for the Christian\u27s faith and life
Parity effect in Al and Nb single electron transistors in a tunable environment
Two different types of Cooper pair transistors, with Al and Nb islands, have
been investigated in a tunable electromagnetic environment. The device with an
Al island demonstrates gate charge modulation with 2e-periodicity in a wide
range of environmental impedances at bath temperatures below 340 mK. Contrary
to the results of the Al sample, we were not able to detect 2e-periodicity
under any conditions on similar samples with Nb island. We attribute this to
the material properties of Nb.Comment: 3 pages, 3 figure
Thermal conductance of a proximity superconductor
We study heat transport in hybrid normal metal - superconductor - normal
metal (NSN) structures. We find the thermal conductance of a short
superconducting wire to be strongly enhanced beyond the BCS value due to
inverse proximity effect. The measurements agree with a model based on the
quasiclassical theory of superconductivity in the diffusive limit. We determine
a crossover temperature below which quasiparticle heat conduction dominates
over the electron-phonon relaxation.Comment: 4+ pages, 3 figure
Comparison of Coulomb Blockade Thermometers with the International Temperature Scale PLTS-2000
The operation of the primary Coulomb blockade thermometer (CBT) is based on a
measurement of bias voltage dependent conductance of arrays of tunnel junctions
between normal metal electrodes. Here we report on a comparison of a CBT with a
high accuracy realization of the PLTS-2000 temperature scale in the range from
0.008 K to 0.65 K. An overall agreement of about 1% was found for temperatures
above 0.25 K. For lower temperatures increasing differences are caused by
thermalization problems which are accounted for by numerical calculations based
on electron-phonon decoupling.Comment: 6 pages, 5 figure
Calorimetric readout of a superconducting proximity-effect thermometer
A proximity-effect thermometer measures the temperature dependent critical
supercurrent in a long superconductor - normal metal - superconductor (SNS)
Josephson junction. Typically, the transition from the superconducting to the
normal state is detected by monitoring the appearance of a voltage across the
junction. We describe a new approach to detect the transition based on the
temperature increase in the resistive state due to Joule heating. Our method
increases the sensitivity and is especially applicable for temperatures below
about 300 mK.Comment: 10 pages, 5 figures. To appear in the proceedings of the Conference
on Micro- and Nanocryogenics (LT25 satellite) organized in Espoo, Finland
(2008
Tunnel Spectroscopy of a Proximity Josephson Junction
We present tunnel spectroscopy experiments on the proximity effect in lateral
superconductor-normal metal-superconductor (SNS) Josephson junctions. Our weak
link is embedded into a superconducting (S) ring allowing phase biasing of the
Josephson junction by an external magnetic field. We explore the temperature
and phase dependence of both the induced mini-gap and the modification of the
density of states in the normal (N) metal. Our results agree with a model based
on the quasiclassical theory in the diffusive limit. The device presents an
advanced version of the superconducting quantum interference proximity
transistor (SQUIPT), now reaching flux sensitivities of 3 nA where
is the flux quantum.Comment: 5 pages, 4 figure
Recombination limited energy relaxation in a BCS superconductor
We study quasiparticle energy relaxation at sub-kelvin temperatures by
injecting hot electrons into an aluminium island and measuring the energy flux
from electrons into phonons both in the superconducting and in the normal
state. The data show strong reduction of the flux at low temperatures in the
superconducting state, in qualitative agreement with the presented
quasiclassical theory for clean superconductors. Quantitatively, the energy
flux exceeds that from the theory both in the superconducting and in the normal
state, possibly suggesting an enhanced or additional relaxation process
The Josephson heat interferometer
The Josephson effect represents perhaps the prototype of macroscopic phase
coherence and is at the basis of the most widespread interferometer, i.e., the
superconducting quantum interference device (SQUID). Yet, in analogy to
electric interference, Maki and Griffin predicted in 1965 that thermal current
flowing through a temperature-biased Josephson tunnel junction is a stationary
periodic function of the quantum phase difference between the superconductors.
The interplay between quasiparticles and Cooper pairs condensate is at the
origin of such phase-dependent heat current, and is unique to Josephson
junctions. In this scenario, a temperature-biased SQUID would allow heat
currents to interfere thus implementing the thermal version of the electric
Josephson interferometer. The dissipative character of heat flux makes this
coherent phenomenon not less extraordinary than its electric (non-dissipative)
counterpart. Albeit weird, this striking effect has never been demonstrated so
far. Here we report the first experimental realization of a heat
interferometer. We investigate heat exchange between two normal metal
electrodes kept at different temperatures and tunnel-coupled to each other
through a thermal `modulator' in the form of a DC-SQUID. Heat transport in the
system is found to be phase dependent, in agreement with the original
prediction. With our design the Josephson heat interferometer yields
magnetic-flux-dependent temperature oscillations of amplitude up to ~21 mK, and
provides a flux-to-temperature transfer coefficient exceeding ~ 60mK/Phi_0 at
235 mK [Phi_0 2* 10^(-15) Wb is the flux quantum]. Besides offering remarkable
insight into thermal transport in Josephson junctions, our results represent a
significant step toward phase-coherent mastering of heat in solid-state
nanocircuits, and pave the way to the design of novel-concept coherent
caloritronic devices.Comment: 4+ pages, 3 color figure
InAs nanowire hot-electron Josephson transistor
At a superconductor (S)-normal metal (N) junction pairing correlations can
"leak-out" into the N region. This proximity effect [1, 2] modifies the system
transport properties and can lead to supercurrent flow in SNS junctions [3].
Recent experimental works showed the potential of semiconductor nanowires (NWs)
as building blocks for nanometre-scale devices [4-7], also in combination with
superconducting elements [8-12]. Here, we demonstrate an InAs NW Josephson
transistor where supercurrent is controlled by hot-quasiparticle injection from
normal-metal electrodes. Operational principle is based on the modification of
NW electron-energy distribution [13-20] that can yield reduced dissipation and
high-switching speed. We shall argue that exploitation of this principle with
heterostructured semiconductor NWs opens the way to a host of
out-of-equilibrium hybrid-nanodevice concepts [7, 21].Comment: 6 pages, 6 color figure
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