4,303 research outputs found
Gain Dependence of the Noise in the Single Electron Transistor
An extensive investigation of low frequency noise in single electron
transistors as a function of gain is presented. Comparing the output noise with
gain for a large number of bias points, it is found that the noise is dominated
by external charge noise. For low gains we find an additional noise
contribution which is compared to a model including resistance fluctuations. We
conclude that this excess noise is not only due to resistance fluctuations. For
one sample, we find a record low minimum charge noise of qn = 9*10^-6
e/sqrt(Hz) in the superconducting state and qn = 9*10^-6 e/sqrt(Hz) in the
normal state at a frequency of 4.4 kHz.Comment: 10 pages, LaTex 2.09, 4 figures (epsfig
Superconducting Electrometer Based on the Resistively Shunted Bloch Transistor
We have fabricated the Bloch transistor shunted on-chip by a small-sized Cr
resistor with Rs about 1 kOhm. The Bloch transistor normally consists of two
small Josephson junctions connected in series, which in our case have been
replaced by two superconducting interferometer loops, each with two junctions
in parallel. A capacitively coupled gate is supplied to control the induced
charge of the small intermediate electrode (island) of the transistor. The
measured I-V curves show no hysteresis and correspond to the operation of a
effective Josephson junction at the high-damping and strong-noise limits. The
critical current of the system was found to be close to its nominal value, that
is in accordance with the electromagnetic environment theory. The I-V curves
were modulated by the gate with a period of e and a maximum swing of about 2
/mu_V. Such rather moderate modulation results from the Josephson-to- charging
energies ratio, Ej/Ec about 9, in our sample being far from its optimum value
of 0.3 up to 1.Comment: To be published in IEEE Transactions on Applied Superconductivity,
June 199
Probing two-field open inflation by resonant signals in correlation functions
This is the author accpted manuscript. The final version is available from IOP Publishing via the DOI in this recordWe derive oscillatory signals in correlation functions in two-field open inflation by means of the in-in formalism; such signatures are caused by resonances between oscillations in the tunnelling field and fluctuations in the inflaton during the curvature dominated, intermediate and subsequent inflationary regime. While amplitudes are model-dependent, we find distinct oscillations in the power and bi-spectrum that can act as a direct probe of the curvature dominated phase and thus, indirectly, strengthen the claim of the string landscape if they were observed. We comment on the prospects of detecting these tell-tale signs in current experiments, which is challenging, but not impossible. At the technical level, we pay special attention to the applicability conditions for truncating fluctuations to the light (inflaton) field and derive upper limits on the oscillation amplitude of the heavy field. A violation of these bounds requires a multi-field analysis at the perturbed level.© 2013 IOP Publishing Ltd and Sissa Medialab srl.Aspen Center for Physic
ON THE SECOND-LARGEST SYLOW SUBGROUP OF A FINITE SIMPLE GROUP OF LIE TYPE
DOI:
10.1017/S000497271800092
Low-cost point-focus solar concentrator, phase 1
The results of the preliminary design study for the low cost point focus solar concentrator (LCPFSC) development program are presented. A summary description of the preliminary design is given. The design philosophy used to achieve a cost effective design for mass production is described. The concentrator meets all design requirements specified and is based on practical design solutions in every possible way
The effect of thermal annealing on the properties of Al-AlOx-Al single electron tunneling transistors
The effect of thermal annealing on the properties of Al-AlOx-Al single
electron tunneling transistors is reported. After treatment of the devices by
annealing processes in forming gas atmosphere at different temperatures and for
different times, distinct and reproducible changes of their resistance and
capacitance values were found. According to the temperature regime, we observed
different behaviors as regards the resistance changes, namely the tendency to
decrease the resistance by annealing at T = 200 degree C, but to increase the
resistance by annealing at T = 400 degree C. We attribute this behavior to
changes in the aluminum oxide barriers of the tunnel junctions. The good
reproducibility of these effects with respect to the changes observed allows
the proper annealing treatment to be used for post-process tuning of tunnel
junction parameters. Also, the influence of the annealing treatment on the
noise properties of the transistors at low frequency was investigated. In no
case did the noise figures in the 1/f-regime show significant changes.Comment: 6 pages, 7 eps-figure
Ultraviolet cut off and Bosonic Dominance
We rederive the thermodynamical properties of a non interacting gas in the
presence of a minimal uncertainty in length. Apart from the phase space measure
which is modified due to a change of the Heisenberg uncertainty relations, the
presence of an ultraviolet cut-off plays a tremendous role.
The theory admits an intrinsic temperature above which the fermion
contribution to energy density, pressure and entropy is negligible.Comment: 12 pages in revtex, 2 figures. Some coefficients have been changed in
the A_2 model and two references adde
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