13,574 research outputs found
Mach-Zehnder interferometry with periodic voltage pulses
We investigate a Mach-Zehnder interferometer driven by a time-dependent
voltage. Motivated by recent experiments, we focus on a train of Lorentzian
voltage pulses which we compare to a sinusoidal and a constant voltage. We
discuss the visibilities of Aharonov-Bohm oscillations in the current and in
the noise. For the current, we find a strikingly different behavior in the
driven as compared to the static case for voltage pulses containing multiple
charges. For pulses containing fractional charges, we find a universality at
path-length differences equal to multiples of the spacing between the voltage
pulses. These observations can be explained by the electronic energy
distribution of the driven contact. In the noise oscillations, we find
additional features which are characteristic to time-dependent transport.
Finite electronic temperatures are found to have a qualitatively different
influence on the current and the noise.Comment: Published version; 11 pages, 5 figure
Efficient circuit triggers high-current, high-voltage pulses
Modified circuit uses diodes to effectively disconnect the charging resistors from the circuit during the discharge cycle. Result is an efficient parallel charging, high voltage pulse modulator with low voltage rating of components
Dynamical control of interference using voltage pulses in the quantum regime
As a general trend, nanoelectronics experiments are shifting toward
frequencies so high that they become comparable to the device's internal
characteristic time scales, resulting in new opportunities for studying the
dynamical aspects of quantum mechanics. Here we theoretically study how a
voltage pulse (in the quantum regime) propagates through an electronic
interferometer (Fabry- Perot or Mach-Zehnder). We show that extremely fast
pulses provide a conceptually new tool for manipulating quantum information:
the possibility to dynamically engineer the interference pattern of a quantum
system. Striking physical signatures are associated with this new regime:
restoration of the interference in presence of large bias voltages; negative
currents with respect to the direction of propagation of the voltage pulse; and
oscillation of the total transmitted charge with the total number of injected
electrons. The present findings have been made possible by the recent unlocking
of our capability for simulating time-resolved quantum nanoelectronics of large
systems.Comment: 11 pages, 9 figure
High-frequency gate manipulation of a bilayer graphene quantum dot
We report transport data obtained for a double-gated bilayer graphene quantum
dot. In Coulomb blockade measurements, the gate dielectric Cytop(TM) is found
to provide remarkable electronic stability even at cryogenic temperatures.
Moreover, we demonstrate gate manipulation with square shaped voltage pulses at
frequencies up to 100 MHz and show that the signal amplitude is not affected by
the presence of the capacitively coupled back gate
Effect of pulsed power on particle matter in diesel engine exhaust using a DBD plasma reactor
Nonthermal plasma (NTP) treatment of exhaust gas is a promising technology for both nitrogen oxides (NOX) and particulate matter (PM) reduction by introducing plasma into the exhaust gases. This paper considers the effect of NTP on PM mass reduction, PM size distribution, and PM removal efficiency. The experiments are performed on real exhaust gases from a diesel engine. The NTP is generated by applying high-voltage pulses using a pulsed power supply across a dielectric barrier discharge (DBD) reactor. The effects of the applied high-voltage pulses up to 19.44 kVpp with repetition rate of 10 kHz are investigated. In this paper, it is shown that the PM removal and PM size distribution need to be considered both together, as it is possible to achieve high PM removal efficiency with undesirable increase in the number of small particles. Regarding these two important factors, in this paper, 17 kVpp voltage level is determined to be an optimum point for the given configuration. Moreover, particles deposition on the surface of the DBD reactor is found to be a significant phenomenon, which should be considered in all plasma PM removal tests
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