1,577 research outputs found
Coherent resistance of a disordered 1D wire: Expressions for all moments and evidence for non-Gaussian distribution
We study coherent electron transport in a one-dimensional wire with disorder
modeled as a chain of randomly positioned scatterers. We derive analytical
expressions for all statistical moments of the wire resistance . By means
of these expressions we show analytically that the distribution of the
variable is not exactly Gaussian even in the limit of weak
disorder. In a strict mathematical sense, this conclusion is found to hold not
only for the distribution tails but also for the bulk of the distribution
.Comment: Revised version, 8 pages, 4 figures, RevTeX
Band-monitoring Payload for a CubeSat Satellite
During changing sun activity, the ionosphere is responding accordingly and therefore it is interesting to observe the propagation behavior of shortwave bands. For the above mentioned purpose we have designed a band-monitoring payload for an experimental CubeSat satellite. The payload consists of a receiver, which is able to receive SSB modulated narrowband signals in 28 MHz uplink band, and a transmitter with FM modulation in UHF downlink band. The receiver frequency is selected to be at the center of radio amateur activity with low data rate digital modulations
X-Band PLL Synthesizer
This paper deals with design and realization of a PLL synthesizer for the microwave X−band. The synthesizer is intended for use as a local oscillator in a K−band downconverter. The design goal was to achieve very low phase noise and spurious free signal with a sufficient power level. For that purpose a low phase noise MMIC VCO was used in phase locked loop. The PLL works at half the output frequency, therefore there is a frequency doubler at the output of the PLL. The output signal from the frequency doubler is filtered by a band-pass filter and finally amplified by a single stage amplifier
Fast Incomplete Decoherence of Nuclear Spins in Quantum Hall Ferromagnet
A scenario of quantum computing process based on the manipulation of a large
number of nuclear spins in Quantum Hall (QH) ferromagnet is presented. It is
found that vacuum quantum fluctuations in the QH ferromagnetic ground state at
filling factor , associated with the virtual excitations of spin waves,
lead to fast incomplete decoherence of the nuclear spins. A fundamental upper
bound on the length of the computer memory is set by this fluctuation effect
- …